从h264码流中获取图像的宽高---版本1 (移植于ffmpeg)

在工程中，我们常常需要知道视频流的宽高，虽然可以借助一些开源库，但是仅为了获取宽高，却需要调用几十或是几百K的开源库，不太划算。因此，本文从开源库中移植了解析264码流宽高的代码，具体如下：

##1 代码源自ffmpeg
###1.1 新建get_bits.h文件

#ifndef AVCODEC_GET_BITS_H
#define AVCODEC_GET_BITS_H#include <stdint.h>#ifdef WIN
#define inline __inline
#else
#define inline
#endiftypedef struct GetBitContext {const uint8_t *buffer, *buffer_end;int index;int size_in_bits;int size_in_bits_plus8;
} GetBitContext;#define FFMAX(a,b) ((a) > (b) ? (a) : (b))
#define FFMAX3(a,b,c) FFMAX(FFMAX(a,b),c)
#define FFMIN(a,b) ((a) > (b) ? (b) : (a))
#define FFMIN3(a,b,c) FFMIN(FFMIN(a,b),c)#ifndef AV_RB32
#   define AV_RB32(x)                                \(((uint32_t)((const uint8_t*)(x))[0] << 24) |    \(((const uint8_t*)(x))[1] << 16) |    \(((const uint8_t*)(x))[2] <<  8) |    \((const uint8_t*)(x))[3])
#endif#define OPEN_READER_NOSIZE(name, gb)            \unsigned int name ## _index = (gb)->index;  \unsigned int /*av_unused*/ name ## _cache#define OPEN_READER(name, gb)                   \OPEN_READER_NOSIZE(name, gb);               \unsigned int name ## _size_plus8 = (gb)->size_in_bits_plus8#define CLOSE_READER(name, gb) (gb)->index = name ## _index# define UPDATE_CACHE_BE(name, gb) name ## _cache = \AV_RB32((gb)->buffer + (name ## _index >> 3)) << (name ## _index & 7)# define UPDATE_CACHE(name, gb) UPDATE_CACHE_BE(name, gb)#   define SKIP_COUNTER(name, gb, num) \name ## _index = FFMIN(name ## _size_plus8, name ## _index + (num))#define LAST_SKIP_BITS(name, gb, num) SKIP_COUNTER(name, gb, num)#define GET_CACHE(name, gb) ((uint32_t) name ## _cache)#   define NEG_USR32(a,s) (((uint32_t)(a))>>(32-(s)))
#define SHOW_UBITS_BE(name, gb, num) NEG_USR32(name ## _cache, num)
#   define SHOW_UBITS(name, gb, num) SHOW_UBITS_BE(name, gb, num)const static uint8_t ff_log2_tab[256]={0,0,1,1,2,2,2,2,3,3,3,3,3,3,3,3,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,4,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,5,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7,7
};const static uint8_t ff_golomb_vlc_len[512] = {19, 17, 15, 15, 13, 13, 13, 13, 11, 11, 11, 11, 11, 11, 11, 11, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9,7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5,3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1
};const static uint8_t ff_ue_golomb_vlc_code[512] = {32, 32, 32, 32, 32, 32, 32, 32, 31, 32, 32, 32, 32, 32, 32, 32, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30,7, 7, 7, 7, 8, 8, 8, 8, 9, 9, 9, 9, 10, 10, 10, 10, 11, 11, 11, 11, 12, 12, 12, 12, 13, 13, 13, 13, 14, 14, 14, 14,3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6, 6,1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0
};const static int8_t ff_se_golomb_vlc_code[512] = {17, 17, 17, 17, 17, 17, 17, 17, 16, 17, 17, 17, 17, 17, 17, 17, 8, -8, 9, -9, 10, -10, 11, -11, 12, -12, 13, -13, 14, -14, 15, -15,4, 4, 4, 4, -4, -4, -4, -4, 5, 5, 5, 5, -5, -5, -5, -5, 6, 6, 6, 6, -6, -6, -6, -6, 7, 7, 7, 7, -7, -7, -7, -7,2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2, -2,3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3, -3,1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
};#ifndef ff_log2
#define ff_log2 ff_log2_c
static /*av_always_inline av_const*/ int ff_log2_c(unsigned int v)
{int n = 0;if (v & 0xffff0000) {v >>= 16;n += 16;}if (v & 0xff00) {v >>= 8;n += 8;}n += ff_log2_tab[v];return n;
}
#endif#define av_log2       ff_log2/**
* Read 1-25 bits.
*/
static inline unsigned int get_bits(GetBitContext *s, int n)
{register int tmp;OPEN_READER(re, s);//av_assert2(n>0 && n <= 25);UPDATE_CACHE(re, s);tmp = SHOW_UBITS(re, s, n);LAST_SKIP_BITS(re, s, n);CLOSE_READER(re, s);return tmp;
}static inline unsigned int get_bits1(GetBitContext *s)
{unsigned int index = s->index;uint8_t result = s->buffer[index >> 3];
#ifdef BITSTREAM_READER_LEresult >>= index & 7;result &= 1;
#elseresult <<= index & 7;result >>= 8 - 1;
#endif
#if 1//!UNCHECKED_BITSTREAM_READERif (s->index < s->size_in_bits_plus8)
#endifindex++;s->index = index;return result;
}static inline void skip_bits(GetBitContext *s, int n)
{OPEN_READER(re, s);LAST_SKIP_BITS(re, s, n);CLOSE_READER(re, s);
}/**
* read unsigned exp golomb code, constraint to a max of 31.
* the return value is undefined if the stored value exceeds 31.
*/
static inline int get_ue_golomb_31(GetBitContext *gb)
{unsigned int buf;OPEN_READER(re, gb);UPDATE_CACHE(re, gb);buf = GET_CACHE(re, gb);buf >>= 32 - 9;LAST_SKIP_BITS(re, gb, ff_golomb_vlc_len[buf]);CLOSE_READER(re, gb);return ff_ue_golomb_vlc_code[buf];
}/**
* Read an unsigned Exp-Golomb code in the range 0 to 8190.
*/
static inline int get_ue_golomb(GetBitContext *gb)
{unsigned int buf;OPEN_READER(re, gb);UPDATE_CACHE(re, gb);buf = GET_CACHE(re, gb);if (buf >= (1 << 27)) {buf >>= 32 - 9;LAST_SKIP_BITS(re, gb, ff_golomb_vlc_len[buf]);CLOSE_READER(re, gb);return ff_ue_golomb_vlc_code[buf];}else {int log = 2 * av_log2(buf) - 31;LAST_SKIP_BITS(re, gb, 32 - log);CLOSE_READER(re, gb);if (log < 7) {//av_log(NULL, AV_LOG_ERROR, "Invalid UE golomb code\n");return -1;//AVERROR_INVALIDDATA;}buf >>= log;buf--;return buf;}
}/**
* read signed exp golomb code.
*/
static inline int get_se_golomb(GetBitContext *gb)
{unsigned int buf;OPEN_READER(re, gb);UPDATE_CACHE(re, gb);buf = GET_CACHE(re, gb);if (buf >= (1 << 27)) {buf >>= 32 - 9;LAST_SKIP_BITS(re, gb, ff_golomb_vlc_len[buf]);CLOSE_READER(re, gb);return ff_se_golomb_vlc_code[buf];}else {int log = av_log2(buf), sign;LAST_SKIP_BITS(re, gb, 31 - log);UPDATE_CACHE(re, gb);buf = GET_CACHE(re, gb);buf >>= log;LAST_SKIP_BITS(re, gb, 32 - log);CLOSE_READER(re, gb);sign = -(buf & 1);buf = ((buf >> 1) ^ sign) - sign;return buf;}
}#endif

###1.2 新建parser_sps.h文件

#ifndef _H264_PARSER_SPS
#define _H264_PARSER_SPS#include <stdint.h>
#include "get_bits.h"#ifdef WIN
#define inline __inline
#else
#define inline
#endif#define MAX_SPS_COUNT     32
#define MAX_LOG2_MAX_FRAME_NUM    (12 + 4)
#define MIN_LOG2_MAX_FRAME_NUM    4#define MAX_DELAYED_PIC_COUNT  16#define FF_ARRAY_ELEMS(a) (sizeof(a) / sizeof((a)[0]))/*** Rational number (pair of numerator and denominator).*/
typedef struct AVRational{int num; ///< Numeratorint den; ///< Denominator
} AVRational;/*** H264Context*/
typedef struct H264Context {GetBitContext gb;// =============================================================// Things below are not used in the MB or more inner codeint nal_ref_idc;int nal_unit_type;uint8_t *rbsp_buffer[2];unsigned int rbsp_buffer_size[2];int is_avc;           ///< this flag is != 0 if codec is avc1int nal_length_size;  ///< Number of bytes used for nal length (1, 2 or 4)
} H264Context;/* NAL unit types */
enum {NAL_SLICE           = 1,NAL_DPA             = 2,NAL_DPB             = 3,NAL_DPC             = 4,NAL_IDR_SLICE       = 5,NAL_SEI             = 6,NAL_SPS             = 7,NAL_PPS             = 8,NAL_AUD             = 9,NAL_END_SEQUENCE    = 10,NAL_END_STREAM      = 11,NAL_FILLER_DATA     = 12,NAL_SPS_EXT         = 13,NAL_AUXILIARY_SLICE = 19,NAL_FF_IGNORE       = 0xff0f001,
};/*** Chromaticity coordinates of the source primaries.*/
enum AVColorPrimaries {AVCOL_PRI_RESERVED0   = 0,AVCOL_PRI_BT709       = 1,  ///< also ITU-R BT1361 / IEC 61966-2-4 / SMPTE RP177 Annex BAVCOL_PRI_UNSPECIFIED = 2,AVCOL_PRI_RESERVED    = 3,AVCOL_PRI_BT470M      = 4,  ///< also FCC Title 47 Code of Federal Regulations 73.682 (a)(20)AVCOL_PRI_BT470BG     = 5,  ///< also ITU-R BT601-6 625 / ITU-R BT1358 625 / ITU-R BT1700 625 PAL & SECAMAVCOL_PRI_SMPTE170M   = 6,  ///< also ITU-R BT601-6 525 / ITU-R BT1358 525 / ITU-R BT1700 NTSCAVCOL_PRI_SMPTE240M   = 7,  ///< functionally identical to aboveAVCOL_PRI_FILM        = 8,  ///< colour filters using Illuminant CAVCOL_PRI_BT2020      = 9,  ///< ITU-R BT2020AVCOL_PRI_SMPTEST428_1 = 10, ///< SMPTE ST 428-1 (CIE 1931 XYZ)AVCOL_PRI_SMPTE431    = 11, ///< SMPTE ST 431-2 (2011)AVCOL_PRI_SMPTE432    = 12, ///< SMPTE ST 432-1 D65 (2010)AVCOL_PRI_NB                ///< Not part of ABI
};/*** Color Transfer Characteristic.*/
enum AVColorTransferCharacteristic {AVCOL_TRC_RESERVED0    = 0,AVCOL_TRC_BT709        = 1,  ///< also ITU-R BT1361AVCOL_TRC_UNSPECIFIED  = 2,AVCOL_TRC_RESERVED     = 3,AVCOL_TRC_GAMMA22      = 4,  ///< also ITU-R BT470M / ITU-R BT1700 625 PAL & SECAMAVCOL_TRC_GAMMA28      = 5,  ///< also ITU-R BT470BGAVCOL_TRC_SMPTE170M    = 6,  ///< also ITU-R BT601-6 525 or 625 / ITU-R BT1358 525 or 625 / ITU-R BT1700 NTSCAVCOL_TRC_SMPTE240M    = 7,AVCOL_TRC_LINEAR       = 8,  ///< "Linear transfer characteristics"AVCOL_TRC_LOG          = 9,  ///< "Logarithmic transfer characteristic (100:1 range)"AVCOL_TRC_LOG_SQRT     = 10, ///< "Logarithmic transfer characteristic (100 * Sqrt(10) : 1 range)"AVCOL_TRC_IEC61966_2_4 = 11, ///< IEC 61966-2-4AVCOL_TRC_BT1361_ECG   = 12, ///< ITU-R BT1361 Extended Colour GamutAVCOL_TRC_IEC61966_2_1 = 13, ///< IEC 61966-2-1 (sRGB or sYCC)AVCOL_TRC_BT2020_10    = 14, ///< ITU-R BT2020 for 10-bit systemAVCOL_TRC_BT2020_12    = 15, ///< ITU-R BT2020 for 12-bit systemAVCOL_TRC_SMPTEST2084  = 16, ///< SMPTE ST 2084 for 10-, 12-, 14- and 16-bit systemsAVCOL_TRC_SMPTEST428_1 = 17, ///< SMPTE ST 428-1AVCOL_TRC_ARIB_STD_B67 = 18, ///< ARIB STD-B67, known as "Hybrid log-gamma"AVCOL_TRC_NB                 ///< Not part of ABI
};/*** YUV colorspace type.*/
enum AVColorSpace {AVCOL_SPC_RGB         = 0,  ///< order of coefficients is actually GBR, also IEC 61966-2-1 (sRGB)AVCOL_SPC_BT709       = 1,  ///< also ITU-R BT1361 / IEC 61966-2-4 xvYCC709 / SMPTE RP177 Annex BAVCOL_SPC_UNSPECIFIED = 2,AVCOL_SPC_RESERVED    = 3,AVCOL_SPC_FCC         = 4,  ///< FCC Title 47 Code of Federal Regulations 73.682 (a)(20)AVCOL_SPC_BT470BG     = 5,  ///< also ITU-R BT601-6 625 / ITU-R BT1358 625 / ITU-R BT1700 625 PAL & SECAM / IEC 61966-2-4 xvYCC601AVCOL_SPC_SMPTE170M   = 6,  ///< also ITU-R BT601-6 525 / ITU-R BT1358 525 / ITU-R BT1700 NTSCAVCOL_SPC_SMPTE240M   = 7,  ///< functionally identical to aboveAVCOL_SPC_YCOCG       = 8,  ///< Used by Dirac / VC-2 and H.264 FRext, see ITU-T SG16AVCOL_SPC_BT2020_NCL  = 9,  ///< ITU-R BT2020 non-constant luminance systemAVCOL_SPC_BT2020_CL   = 10, ///< ITU-R BT2020 constant luminance systemAVCOL_SPC_SMPTE2085   = 11, ///< SMPTE 2085, Y'D'zD'xAVCOL_SPC_NB                ///< Not part of ABI
};/*** Sequence parameter set*/
typedef struct SPS {unsigned int sps_id;int profile_idc;int level_idc;int chroma_format_idc;int transform_bypass;              ///< qpprime_y_zero_transform_bypass_flagint log2_max_frame_num;            ///< log2_max_frame_num_minus4 + 4int poc_type;                      ///< pic_order_cnt_typeint log2_max_poc_lsb;              ///< log2_max_pic_order_cnt_lsb_minus4int delta_pic_order_always_zero_flag;int offset_for_non_ref_pic;int offset_for_top_to_bottom_field;int poc_cycle_length;              ///< num_ref_frames_in_pic_order_cnt_cycleint ref_frame_count;               ///< num_ref_framesint gaps_in_frame_num_allowed_flag;int mb_width;                      ///< pic_width_in_mbs_minus1 + 1int mb_height;                     ///< pic_height_in_map_units_minus1 + 1int frame_mbs_only_flag;int mb_aff;                        ///< mb_adaptive_frame_field_flagint direct_8x8_inference_flag;int crop;                          ///< frame_cropping_flagint width, height;/* those 4 are already in luma samples */unsigned int crop_left;            ///< frame_cropping_rect_left_offsetunsigned int crop_right;           ///< frame_cropping_rect_right_offsetunsigned int crop_top;             ///< frame_cropping_rect_top_offsetunsigned int crop_bottom;          ///< frame_cropping_rect_bottom_offsetint vui_parameters_present_flag;AVRational sar;int video_signal_type_present_flag;int full_range;int colour_description_present_flag;enum AVColorPrimaries color_primaries;enum AVColorTransferCharacteristic color_trc;enum AVColorSpace colorspace;int timing_info_present_flag;uint32_t num_units_in_tick;uint32_t time_scale;int fixed_frame_rate_flag;short offset_for_ref_frame[256]; // FIXME dyn aloc?int bitstream_restriction_flag;int num_reorder_frames;int scaling_matrix_present;uint8_t scaling_matrix4[6][16];uint8_t scaling_matrix8[6][64];int nal_hrd_parameters_present_flag;int vcl_hrd_parameters_present_flag;int pic_struct_present_flag;int time_offset_length;int cpb_cnt;                          ///< See H.264 E.1.2int initial_cpb_removal_delay_length; ///< initial_cpb_removal_delay_length_minus1 + 1int cpb_removal_delay_length;         ///< cpb_removal_delay_length_minus1 + 1int dpb_output_delay_length;          ///< dpb_output_delay_length_minus1 + 1int bit_depth_luma;                   ///< bit_depth_luma_minus8 + 8int bit_depth_chroma;                 ///< bit_depth_chroma_minus8 + 8int residual_color_transform_flag;    ///< residual_colour_transform_flagint constraint_set_flags;             ///< constraint_set[0-3]_flaguint8_t data[4096];size_t data_size;
} SPS;void *h264Ps_Open();
int h264Ps_Parser(H264Context *h, const uint8_t * const buf, int buf_size, H264SPS *sps);
void h264Ps_Close(void *handle);#endif

###1.3 新建parser_sps.c文件

#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include "get_bits.h"
#include "parser_sps.h"static const uint8_t default_scaling4[2][16] = {{  6, 13, 20, 28, 13, 20, 28, 32,20, 28, 32, 37, 28, 32, 37, 42 },{ 10, 14, 20, 24, 14, 20, 24, 27,20, 24, 27, 30, 24, 27, 30, 34 }
};static const uint8_t default_scaling8[2][64] = {{  6, 10, 13, 16, 18, 23, 25, 27,10, 11, 16, 18, 23, 25, 27, 29,13, 16, 18, 23, 25, 27, 29, 31,16, 18, 23, 25, 27, 29, 31, 33,18, 23, 25, 27, 29, 31, 33, 36,23, 25, 27, 29, 31, 33, 36, 38,25, 27, 29, 31, 33, 36, 38, 40,27, 29, 31, 33, 36, 38, 40, 42 },{  9, 13, 15, 17, 19, 21, 22, 24,13, 13, 17, 19, 21, 22, 24, 25,15, 17, 19, 21, 22, 24, 25, 27,17, 19, 21, 22, 24, 25, 27, 28,19, 21, 22, 24, 25, 27, 28, 30,21, 22, 24, 25, 27, 28, 30, 32,22, 24, 25, 27, 28, 30, 32, 33,24, 25, 27, 28, 30, 32, 33, 35 }
};static const uint8_t ff_zigzag_direct[64] = {0,   1,  8, 16,  9,  2,  3, 10,17, 24, 32, 25, 18, 11,  4,  5,12, 19, 26, 33, 40, 48, 41, 34,27, 20, 13,  6,  7, 14, 21, 28,35, 42, 49, 56, 57, 50, 43, 36,29, 22, 15, 23, 30, 37, 44, 51,58, 59, 52, 45, 38, 31, 39, 46,53, 60, 61, 54, 47, 55, 62, 63
};static const uint8_t ff_zigzag_scan[16+1] = {0 + 0 * 4, 1 + 0 * 4, 0 + 1 * 4, 0 + 2 * 4,1 + 1 * 4, 2 + 0 * 4, 3 + 0 * 4, 2 + 1 * 4,1 + 2 * 4, 0 + 3 * 4, 1 + 3 * 4, 2 + 2 * 4,3 + 1 * 4, 3 + 2 * 4, 2 + 3 * 4, 3 + 3 * 4,
};static int decode_scaling_list(GetBitContext *gb, uint8_t *factors, int size,const uint8_t *jvt_list,const uint8_t *fallback_list)
{int i, last = 8, next = 8;const uint8_t *scan = size == 16 ? ff_zigzag_scan : ff_zigzag_direct;if (!get_bits1(gb)) /* matrix not written, we use the predicted one */memcpy(factors, fallback_list, size * sizeof(uint8_t));elsefor (i = 0; i < size; i++) {if (next) {int v = get_se_golomb(gb);if (v < -128 || v > 127) {return -1;}next = (last + v) & 0xff;}if (!i && !next) { /* matrix not written, we use the preset one */memcpy(factors, jvt_list, size * sizeof(uint8_t));break;}last = factors[scan[i]] = next ? next : last;}return 0;
}/* returns non zero if the provided SPS scaling matrix has been filled */
static int decode_scaling_matrices(GetBitContext *gb, const SPS *sps,void *pps, int is_sps,uint8_t(*scaling_matrix4)[16],uint8_t(*scaling_matrix8)[64])
{int transform_8x8_mode = 0;int fallback_sps = !is_sps && sps->scaling_matrix_present;const uint8_t *fallback[4] = {fallback_sps ? sps->scaling_matrix4[0] : default_scaling4[0],fallback_sps ? sps->scaling_matrix4[3] : default_scaling4[1],fallback_sps ? sps->scaling_matrix8[0] : default_scaling8[0],fallback_sps ? sps->scaling_matrix8[3] : default_scaling8[1]};int ret = 0;if (get_bits1(gb)) {ret |= decode_scaling_list(gb, scaling_matrix4[0], 16, default_scaling4[0], fallback[0]);        // Intra, Yret |= decode_scaling_list(gb, scaling_matrix4[1], 16, default_scaling4[0], scaling_matrix4[0]); // Intra, Crret |= decode_scaling_list(gb, scaling_matrix4[2], 16, default_scaling4[0], scaling_matrix4[1]); // Intra, Cbret |= decode_scaling_list(gb, scaling_matrix4[3], 16, default_scaling4[1], fallback[1]);        // Inter, Yret |= decode_scaling_list(gb, scaling_matrix4[4], 16, default_scaling4[1], scaling_matrix4[3]); // Inter, Crret |= decode_scaling_list(gb, scaling_matrix4[5], 16, default_scaling4[1], scaling_matrix4[4]); // Inter, Cbif (is_sps || transform_8x8_mode) {ret |= decode_scaling_list(gb, scaling_matrix8[0], 64, default_scaling8[0], fallback[2]); // Intra, Yret |= decode_scaling_list(gb, scaling_matrix8[3], 64, default_scaling8[1], fallback[3]); // Inter, Yif (sps->chroma_format_idc == 3) {ret |= decode_scaling_list(gb, scaling_matrix8[1], 64, default_scaling8[0], scaling_matrix8[0]); // Intra, Crret |= decode_scaling_list(gb, scaling_matrix8[4], 64, default_scaling8[1], scaling_matrix8[3]); // Inter, Crret |= decode_scaling_list(gb, scaling_matrix8[2], 64, default_scaling8[0], scaling_matrix8[1]); // Intra, Cbret |= decode_scaling_list(gb, scaling_matrix8[5], 64, default_scaling8[1], scaling_matrix8[4]); // Inter, Cb}}if (!ret)ret = is_sps;}return ret;
}int ff_h264_decode_seq_parameter_set(GetBitContext *gb, SPS* sps)
{int profile_idc, level_idc, constraint_set_flags = 0, reserved_zero_2bits;unsigned int sps_id;int i, log2_max_frame_num_minus4;  profile_idc           = get_bits(gb, 8);constraint_set_flags |= get_bits1(gb) << 0;   // constraint_set0_flagconstraint_set_flags |= get_bits1(gb) << 1;   // constraint_set1_flagconstraint_set_flags |= get_bits1(gb) << 2;   // constraint_set2_flagconstraint_set_flags |= get_bits1(gb) << 3;   // constraint_set3_flagconstraint_set_flags |= get_bits1(gb) << 4;   // constraint_set4_flagconstraint_set_flags |= get_bits1(gb) << 5;   // constraint_set5_flag//reserved_zero_2bits     = h264_bs_read_u(gb,2);skip_bits(gb, 2);                             // reserved_zero_2bitslevel_idc = get_bits(gb, 8);sps_id    = get_ue_golomb_31(gb);if (sps_id >= MAX_SPS_COUNT) {goto fail;}sps->sps_id               = sps_id;sps->time_offset_length   = 24;sps->profile_idc          = profile_idc;sps->constraint_set_flags = constraint_set_flags;sps->level_idc            = level_idc;sps->full_range           = -1;memset(sps->scaling_matrix4, 16, sizeof(sps->scaling_matrix4));memset(sps->scaling_matrix8, 16, sizeof(sps->scaling_matrix8));sps->scaling_matrix_present = 0;sps->colorspace = 2; //AVCOL_SPC_UNSPECIFIEDif (sps->profile_idc == 100 ||  // High profilesps->profile_idc == 110 ||  // High10 profilesps->profile_idc == 122 ||  // High422 profilesps->profile_idc == 244 ||  // High444 Predictive profilesps->profile_idc ==  44 ||  // Cavlc444 profilesps->profile_idc ==  83 ||  // Scalable Constrained High profile (SVC)sps->profile_idc ==  86 ||  // Scalable High Intra profile (SVC)sps->profile_idc == 118 ||  // Stereo High profile (MVC)sps->profile_idc == 128 ||  // Multiview High profile (MVC)sps->profile_idc == 138 ||  // Multiview Depth High profile (MVCD)sps->profile_idc == 144) {  // old High444 profilesps->chroma_format_idc = get_ue_golomb_31(gb);if (sps->chroma_format_idc > 3U) {goto fail;} else if (sps->chroma_format_idc == 3) {sps->residual_color_transform_flag = get_bits1(gb);if (sps->residual_color_transform_flag) {goto fail;}}sps->bit_depth_luma   = get_ue_golomb(gb) + 8;sps->bit_depth_chroma = get_ue_golomb(gb) + 8;if (sps->bit_depth_chroma != sps->bit_depth_luma) {goto fail;}if (sps->bit_depth_luma   < 8 || sps->bit_depth_luma   > 14 ||sps->bit_depth_chroma < 8 || sps->bit_depth_chroma > 14) {goto fail;}sps->transform_bypass = get_bits1(gb);sps->scaling_matrix_present |= decode_scaling_matrices(gb, sps, NULL, 1,sps->scaling_matrix4, sps->scaling_matrix8);} else {sps->chroma_format_idc = 1;sps->bit_depth_luma    = 8;sps->bit_depth_chroma  = 8;}log2_max_frame_num_minus4 = get_ue_golomb(gb);if (log2_max_frame_num_minus4 < MIN_LOG2_MAX_FRAME_NUM - 4 ||log2_max_frame_num_minus4 > MAX_LOG2_MAX_FRAME_NUM - 4) {goto fail;}sps->log2_max_frame_num = log2_max_frame_num_minus4 + 4;sps->poc_type = get_ue_golomb_31(gb);if (sps->poc_type == 0) { // FIXME #defineunsigned t = get_ue_golomb(gb);if (t>12) {goto fail;}sps->log2_max_poc_lsb = t + 4;} else if (sps->poc_type == 1) { // FIXME #definesps->delta_pic_order_always_zero_flag = get_bits1(gb);sps->offset_for_non_ref_pic           = get_se_golomb(gb);sps->offset_for_top_to_bottom_field   = get_se_golomb(gb);sps->poc_cycle_length                 = get_ue_golomb(gb);if ((unsigned)sps->poc_cycle_length >=FF_ARRAY_ELEMS(sps->offset_for_ref_frame)) {goto fail;}for (i = 0; i < sps->poc_cycle_length; i++)sps->offset_for_ref_frame[i] = get_se_golomb(gb);} else if (sps->poc_type != 2) {goto fail;}sps->ref_frame_count = get_ue_golomb_31(gb);if (sps->ref_frame_count > MAX_DELAYED_PIC_COUNT) {goto fail;}sps->gaps_in_frame_num_allowed_flag = get_bits1(gb);sps->mb_width                       = get_ue_golomb(gb) + 1;sps->mb_height                      = get_ue_golomb(gb) + 1;sps->frame_mbs_only_flag = get_bits1(gb);sps->mb_height *= 2 - sps->frame_mbs_only_flag;if (!sps->frame_mbs_only_flag)sps->mb_aff = get_bits1(gb);elsesps->mb_aff = 0;if ((unsigned)sps->mb_width  >= INT_MAX / 16 ||(unsigned)sps->mb_height >= INT_MAX / (16 * (2 - sps->frame_mbs_only_flag)) ) {goto fail;}sps->direct_8x8_inference_flag = get_bits1(gb);sps->crop = get_bits1(gb);sps->width =  16 * sps->mb_width;sps->height = 16 * sps->mb_height;if (sps->crop) {unsigned int crop_left   = get_ue_golomb(gb);unsigned int crop_right  = get_ue_golomb(gb);unsigned int crop_top    = get_ue_golomb(gb);unsigned int crop_bottom = get_ue_golomb(gb);int width  = 16 * sps->mb_width;int height = 16 * sps->mb_height * (2 - sps->frame_mbs_only_flag);sps->width = width;sps->height = height;if (0) {sps->crop_left   =sps->crop_right  =sps->crop_top    =sps->crop_bottom = 0;} else {int vsub   = (sps->chroma_format_idc == 1) ? 1 : 0;int hsub   = (sps->chroma_format_idc == 1 ||sps->chroma_format_idc == 2) ? 1 : 0;int step_x = 1 << hsub;int step_y = (2 - sps->frame_mbs_only_flag) << vsub;if (crop_left & (0x1F >> (sps->bit_depth_luma > 8))) {crop_left &= ~(0x1F >> (sps->bit_depth_luma > 8));}if (crop_left  > (unsigned)INT_MAX / 4 / step_x ||crop_right > (unsigned)INT_MAX / 4 / step_x ||crop_top   > (unsigned)INT_MAX / 4 / step_y ||crop_bottom> (unsigned)INT_MAX / 4 / step_y ||(crop_left + crop_right ) * step_x >= width ||(crop_top  + crop_bottom) * step_y >= height) {goto fail;}sps->crop_left   = crop_left   * step_x;sps->crop_right  = crop_right  * step_x;sps->crop_top    = crop_top    * step_y;sps->crop_bottom = crop_bottom * step_y;}} else {sps->crop_left   =sps->crop_right  =sps->crop_top    =sps->crop_bottom =sps->crop        = 0;}sps->vui_parameters_present_flag = get_bits1(gb);if (sps->vui_parameters_present_flag) {int ret = 0;//decode_vui_parameters(gb, avctx, sps);if (ret < 0)goto fail;}return 0;fail:return -1;
}/*** Initialize GetBitContext.* @param buffer bitstream buffer, must be FF_INPUT_BUFFER_PADDING_SIZE bytes*        larger than the actual read bits because some optimized bitstream*        readers read 32 or 64 bit at once and could read over the end* @param bit_size the size of the buffer in bits* @return 0 on success, AVERROR_INVALIDDATA if the buffer_size would overflow.*/
static /*inline*/ int init_get_bits(GetBitContext *s, const uint8_t *buffer,int bit_size)
{int buffer_size;int ret = 0;if (bit_size >= INT_MAX - 7 || bit_size < 0 || !buffer) {bit_size    = 0;buffer      = NULL;ret         = -1;//AVERROR_INVALIDDATA;}buffer_size = (bit_size + 7) >> 3;s->buffer             = buffer;s->size_in_bits       = bit_size;s->size_in_bits_plus8 = bit_size + 8;s->buffer_end         = buffer + buffer_size;s->index              = 0;return ret;
}static inline int get_avc_nalsize(H264Context *h, const uint8_t *buf,int buf_size, int *buf_index)
{int i, nalsize = 0;if (*buf_index >= buf_size - h->nal_length_size)return -1;for (i = 0; i < h->nal_length_size; i++)nalsize = ((unsigned)nalsize << 8) | buf[(*buf_index)++];if (nalsize <= 0 || nalsize > buf_size - *buf_index) {/*av_log(h->avctx, AV_LOG_ERROR,"AVC: nal size %d\n", nalsize);*/return -1;}return nalsize;
}const uint8_t *avpriv_find_start_code(const uint8_t */*av_restrict*/ p,const uint8_t *end,uint32_t */*av_restrict*/ state)
{int i;//av_assert0(p <= end);if (p >= end)return end;for (i = 0; i < 3; i++) {uint32_t tmp = *state << 8;*state = tmp + *(p++);if (tmp == 0x100 || p == end)return p;}while (p < end) {if      (p[-1] > 1      ) p += 3;else if (p[-2]          ) p += 2;else if (p[-3]|(p[-1]-1)) p++;else {p++;break;}}p = FFMIN(p, end) - 4;*state = AV_RB32(p);return p + 4;
}static inline int find_start_code(const uint8_t *buf, int buf_size,int buf_index, int next_avc)
{uint32_t state = -1;buf_index = avpriv_find_start_code(buf + buf_index, buf + next_avc + 1, &state) - buf - 1;return FFMIN(buf_index, buf_size);
}#define FF_INPUT_BUFFER_PADDING_SIZE 32
#define MAX_MBPAIR_SIZE (256*1024) // a tighter bound could be calculated if someone cares about a few bytesstatic size_t max_alloc_size= INT_MAX;
void *av_malloc(size_t size)
{void *ptr = NULL;
#if CONFIG_MEMALIGN_HACKlong diff;
#endif/* let's disallow possibly ambiguous cases */if (size > (max_alloc_size - 32))return NULL;#if CONFIG_MEMALIGN_HACKptr = malloc(size + ALIGN);if (!ptr)return ptr;diff              = ((~(long)ptr)&(ALIGN - 1)) + 1;ptr               = (char *)ptr + diff;((char *)ptr)[-1] = diff;
#elif HAVE_POSIX_MEMALIGNif (size) //OS X on SDK 10.6 has a broken posix_memalign implementationif (posix_memalign(&ptr, ALIGN, size))ptr = NULL;
#elif HAVE_ALIGNED_MALLOCptr = _aligned_malloc(size, ALIGN);
#elif HAVE_MEMALIGN
#ifndef __DJGPP__ptr = memalign(ALIGN, size);
#elseptr = memalign(size, ALIGN);
#endif/* Why 64?* Indeed, we should align it:*   on  4 for 386*   on 16 for 486*   on 32 for 586, PPro - K6-III*   on 64 for K7 (maybe for P3 too).* Because L1 and L2 caches are aligned on those values.* But I don't want to code such logic here!*//* Why 32?* For AVX ASM. SSE / NEON needs only 16.* Why not larger? Because I did not see a difference in benchmarks ...*//* benchmarks with P3* memalign(64) + 1          3071, 3051, 3032* memalign(64) + 2          3051, 3032, 3041* memalign(64) + 4          2911, 2896, 2915* memalign(64) + 8          2545, 2554, 2550* memalign(64) + 16         2543, 2572, 2563* memalign(64) + 32         2546, 2545, 2571* memalign(64) + 64         2570, 2533, 2558** BTW, malloc seems to do 8-byte alignment by default here.*/
#elseptr = malloc(size);
#endifif(!ptr && !size) {size = 1;ptr= av_malloc(1);}
#if CONFIG_MEMORY_POISONINGif (ptr)memset(ptr, FF_MEMORY_POISON, size);
#endifreturn ptr;
}void *av_mallocz(size_t size)
{void *ptr = av_malloc(size);if (ptr)memset(ptr, 0, size);return ptr;
}void av_free(void *ptr)
{
#if CONFIG_MEMALIGN_HACKif (ptr) {int v= ((char *)ptr)[-1];av_assert0(v>0 && v<=ALIGN);free((char *)ptr - v);}
#elif HAVE_ALIGNED_MALLOC_aligned_free(ptr);
#elsefree(ptr);
#endif
}void av_freep(void *arg)
{void **ptr = (void **)arg;av_free(*ptr);*ptr = NULL;
}static inline int ff_fast_malloc(void *ptr, unsigned int *size, size_t min_size, int zero_realloc)
{void **p = ptr;if (min_size <= *size && *p)return 0;min_size = FFMAX(17 * min_size / 16 + 32, min_size);av_free(*p);*p = zero_realloc ? av_mallocz(min_size) : av_malloc(min_size);if (!*p)min_size = 0;*size = min_size;return 1;
}void av_fast_padded_malloc(void *ptr, unsigned int *size, size_t min_size)
{uint8_t **p = ptr;if (min_size > SIZE_MAX - FF_INPUT_BUFFER_PADDING_SIZE) {av_freep(p);*size = 0;return;}if (!ff_fast_malloc(p, size, min_size + FF_INPUT_BUFFER_PADDING_SIZE, 1))memset(*p + min_size, 0, FF_INPUT_BUFFER_PADDING_SIZE);
}const uint8_t *ff_h264_decode_nal(H264Context *h, const uint8_t *src,int *dst_length, int *consumed, int length)
{int i, si, di;uint8_t *dst;int bufidx;// src[0]&0x80; // forbidden bith->nal_ref_idc   = src[0] >> 5;h->nal_unit_type = src[0] & 0x1F;src++;length--;#define STARTCODE_TEST                                                  \if (i + 2 < length && src[i + 1] == 0 && src[i + 2] <= 3) {         \if (src[i + 2] != 3 && src[i + 2] != 0) {                       \/* startcode, so we must be past the end */                 \length = i;                                                 \}                                                               \break;                                                          \}#if HAVE_FAST_UNALIGNED
#define FIND_FIRST_ZERO                                                 \if (i > 0 && !src[i])                                               \i--;                                                            \while (src[i])                                                      \i++#if HAVE_FAST_64BITfor (i = 0; i + 1 < length; i += 9) {if (!((~AV_RN64A(src + i) &(AV_RN64A(src + i) - 0x0100010001000101ULL)) &0x8000800080008080ULL))continue;FIND_FIRST_ZERO;STARTCODE_TEST;i -= 7;}
#elsefor (i = 0; i + 1 < length; i += 5) {if (!((~AV_RN32A(src + i) &(AV_RN32A(src + i) - 0x01000101U)) &0x80008080U))continue;FIND_FIRST_ZERO;STARTCODE_TEST;i -= 3;}
#endif
#elsefor (i = 0; i + 1 < length; i += 2) {if (src[i])continue;if (i > 0 && src[i - 1] == 0)i--;STARTCODE_TEST;}
#endif// use second escape buffer for inter databufidx = h->nal_unit_type == NAL_DPC ? 1 : 0;av_fast_padded_malloc(&h->rbsp_buffer[bufidx], &h->rbsp_buffer_size[bufidx], length+MAX_MBPAIR_SIZE);dst = h->rbsp_buffer[bufidx];if (!dst)return NULL;if(i>=length-1){ //no escaped 0*dst_length= length;*consumed= length+1; //+1 for the headerif(1/*h->avctx->flags2 & CODEC_FLAG2_FAST*/){return src;}else{memcpy(dst, src, length);return dst;}}memcpy(dst, src, i);si = di = i;while (si + 2 < length) {// remove escapes (very rare 1:2^22)if (src[si + 2] > 3) {dst[di++] = src[si++];dst[di++] = src[si++];} else if (src[si] == 0 && src[si + 1] == 0 && src[si + 2] != 0) {if (src[si + 2] == 3) { // escapedst[di++]  = 0;dst[di++]  = 0;si        += 3;continue;} else // next start codegoto nsc;}dst[di++] = src[si++];}while (si < length)dst[di++] = src[si++];nsc:memset(dst + di, 0, FF_INPUT_BUFFER_PADDING_SIZE);*dst_length = di;*consumed   = si + 1; // +1 for the header/* FIXME store exact number of bits in the getbitcontext* (it is needed for decoding) */return dst;
}int h264Ps_Parser(H264Context *h, const uint8_t * const buf, int buf_size, H264SPS *sps)
{//H264Context *h         = s->priv_data;int buf_index, next_avc;unsigned int pps_id;unsigned int slice_type;int state = -1, got_reset = 0;const uint8_t *ptr;//int q264 = buf_size >=4 && !memcmp("Q264", buf, 4);int field_poc[2];/* set some sane default values *///s->pict_type         = AV_PICTURE_TYPE_I;//s->key_frame         = 0;//s->picture_structure = AV_PICTURE_STRUCTURE_UNKNOWN;//h->avctx = avctx;//ff_h264_reset_sei(h);//h->sei_fpa.frame_packing_arrangement_cancel_flag = -1;if (!buf_size)return 0;buf_index     = 0;next_avc      = h->is_avc ? 0 : buf_size;for (;;) {int src_length, dst_length, consumed, nalsize = 0;if (buf_index >= next_avc) {nalsize = get_avc_nalsize(h, buf, buf_size, &buf_index);if (nalsize < 0)break;next_avc = buf_index + nalsize;} else {buf_index = find_start_code(buf, buf_size, buf_index, next_avc);if (buf_index >= buf_size)break;if (buf_index >= next_avc)continue;}src_length = next_avc - buf_index;state = buf[buf_index];switch (state & 0x1f) {case NAL_SLICE:case NAL_IDR_SLICE:// Do not walk the whole buffer just to decode slice headerif ((state & 0x1f) == NAL_IDR_SLICE || ((state >> 5) & 0x3) == 0) {/* IDR or disposable slice* No need to decode many bytes because MMCOs shall not be present. */if (src_length > 60)src_length = 60;} else {/* To decode up to MMCOs */if (src_length > 1000)src_length = 1000;}break;}ptr = ff_h264_decode_nal(h, buf + buf_index, &dst_length,&consumed, src_length);if (!ptr || dst_length < 0)break;buf_index += consumed;init_get_bits(&h->gb, ptr, 8 * dst_length);switch (h->nal_unit_type) {case NAL_SPS:ff_h264_decode_seq_parameter_set(h, sps);break;}}//if (q264)//    return 0;/* didn't find a picture! *///av_log(h->avctx, AV_LOG_ERROR, "missing picture in access unit with size %d\n", buf_size);return -1;
}void *h264Ps_Open()
{H264Context *h;h = (H264Context *)malloc(sizeof(*h));if(h == NULL){return NULL;}memset(h, 0, sizeof(*h));return h;
}void h264Ps_Close(void *handle)
{H264Context *h = (H264Context*)handle;if(h){av_freep(&h->rbsp_buffer[1]);av_freep(&h->rbsp_buffer[0]);h->rbsp_buffer_size[0] = 0;h->rbsp_buffer_size[1] = 0;free(h);}
}

###1.4 新建parser_demo.c文件

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include "parser_sps.h"void ParserH264Resolution(char *cpFileName, int *ipWidth, int *ipHeight)
{   FILE *fp;long len;unsigned char *buf;H264Context *h;H264SPS  sps;fp = fopen(cpFileName,"rb");fseek(fp,0,SEEK_END);len = ftell(fp);fseek(fp,0,SEEK_SET);buf = (unsigned char*) malloc (len+1);fread(buf,1,len,fp);fclose(fp);h = h264Ps_Open();if(h == NULL){printf("[h264Ps can't malloc memory!\n]");}h264Ps_Parser(h, buf, len, &sps);h264Ps_Close(h);free(buf);return;
}int main(int argc, char *argv[])
{int iHeight=0, iWidth=0;char *cpFileName = argv[1];ParserH264Resolution(cpFileName, &iWidth, &iHeight);return 0;
}

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