我正在通过USB Terratec Grabster AV350(基于em2860芯片)捕获视频.

播放时我没有成功获取音频.如果我使用vlc或ffplay播放捕获的视频,我只有3秒钟的声音,然后对视频的其余部分保持沉默……

在捕获过程中,我没有收到任何错误.最后它表明了录制的视频和音频的大小….

我正在使用ffmpeg命令：

ffmpeg -f alsa -ac 2 -i hw：3 -f video4linux2 -i / dev / video0 -acodec ac3 -ab 128k -vcodec mpeg4 -b 6000k -r 25 test5.avi

日志是：

[alsa @ 0x9bcd420]Estimating duration from bitrate, this may be inaccurate

Input #0, alsa, from 'hw:3':

Duration: N/A, start: 69930.998994, bitrate: N/A

Stream #0.0: Audio: pcm_s16le, 44100 Hz, 2 channels, s16, 1411 kb/s

[video4linux2 @ 0x9bf5d30]Estimating duration from bitrate, this may be inaccurate

Input #1, video4linux2, from '/dev/video0':

Duration: N/A, start: 1307111377.654173, bitrate: -2147483 kb/s

Stream #1.0: Video: rawvideo, yuyv422, 720x576, -2147483 kb/s, 1000k tbr, 1000k tbn, 1000k tbc

[ac3 @ 0x9bf9590]No channel layout specified. The encoder will guess the layout, but it might be incorrect.

Output #0, avi, to 'test5.avi':

Metadata:

ISFT : Lavf52.64.2

Stream #0.0: Video: mpeg4, yuv420p, 720x576, q=2-31, 6000 kb/s, 25 tbn, 25 tbc

Stream #0.1: Audio: ac3, 44100 Hz, stereo, s16, 128 kb/s

Stream mapping:

Stream #1.0 -> #0.0

Stream #0.0 -> #0.1

Press [q] to stop encoding

frame= 1283 fps= 25 q=2.3 Lsize= 38677kB time=51.32 bitrate=6173.9kbits/s

**video:37755kB audio:846kB** global headers:0kB muxing overhead 0.198922%

如果我减少仅捕获音频的命令,则可以成功播放音频文件：

ffmpeg -f alsa -ac 2 -i hw：3,0 -acodec ac3 -ab 128k test5.avi

[alsa @ 0x8ede420]Estimating duration from bitrate, this may be inaccurate

Input #0, alsa, from 'hw:3,0':

Duration: N/A, start: 70395.998935, bitrate: N/A

Stream #0.0: Audio: pcm_s16le, 44100 Hz, 2 channels, s16, 1411 kb/s

[ac3 @ 0x8eebac0]No channel layout specified. The encoder will guess the layout, but it might be incorrect.

Output #0, avi, to 'test5.avi':

Metadata:

ISFT : Lavf52.64.2

Stream #0.0: Audio: ac3, 44100 Hz, stereo, s16, 128 kb/s

Stream mapping:

Stream #0.0 -> #0.0

Press [q] to stop encoding

size= 227kB time=13.62 bitrate= 136.8kbits/s

**video:0kB audio:213kB** global headers:0kB muxing overhead 6.902375%

如果我只运行命令进行视频捕获,那么vlc或ffplay可以成功播放视频：

ffmpeg -f video4linux2 -i / dev / video0 -vcodec mpeg4 -b 12000k -r 25 test5.avi

[video4linux2 @ 0x91d6420]Estimating duration from bitrate, this may be inaccurate

Input #0, video4linux2, from '/dev/video0':

Duration: N/A, start: 1307112044.025687, bitrate: -2147483 kb/s

Stream #0.0: Video: rawvideo, yuyv422, 720x576, -2147483 kb/s, 1000k tbr, 1000k tbn, 1000k tbc

Output #0, avi, to 'test5.avi':

Metadata:

ISFT : Lavf52.64.2

Stream #0.0: Video: mpeg4, yuv420p, 720x576, q=2-31, 12000 kb/s, 25 tbn, 25 tbc

Stream mapping:

Stream #0.0 -> #0.0

Press [q] to stop encoding

frame= 388 fps= 25 q=2.0 Lsize= 12963kB time=15.52 bitrate=6842.5kbits/s

**video:12949kB audio:0kB** global headers:0kB muxing overhead 0.114584%

我注意到的奇怪行为是,当我尝试捕获视频和音频时,我无法再捕获音频了,

除非我先拔下AV350.

G350位于卡3：

htpc@htpc-01:/proc/asound/G350/pcm0c$more info

card: 3

device: 0

subdevice: 0

stream: CAPTURE

id: USB Audio

name: USB Audio

subname: subdevice #0

class: 0

subclass: 0

subdevices_count: 1

subdevices_avail: 1

操作系统是Linux 2.6.38-8-Ubuntu Natty Narwhal版本

任何有关如何解决这个问题的帮助都会很棒….

谢谢 ！