How can I record audio and video simultaneously with ffmpeg from linux linux capture device

Question

I am shooting a video using the USB Terratec Grabster AV350 (which is based on the em2860 chip).

I can’t get the sound when it is playing. If I play the captured video using vlc or with ffplay, I get only 3 seconds of sound, and then silence for the rest of the video ...

I do not get any errors during capture. At the end, this indicates the size of the video and audio recorded ....

I use the ffmpeg command for this:

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

Journal:

[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% 

If I reduce the command only for recording sound, then the sound file can be played successfully:

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% 

If I run the command only to capture video, then vlc or ffplay can successfully play the video:

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% 

The strange behavior that I noticed is that when I tried to capture video and audio, I can no longer record audio if I first turn off the AV350.

G350 is on map 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 

OS is Linux 2.6.38-8-generic with Ubuntu Natty Narwhal

Any help to solve this problem would be great.

Thanks!

Answer 1

I was working on something like this, and I used this command:

 ffmpeg -y -f alsa -i default -f v4l2 -i /dev/video0 -acodec aac -strict -2 -ac 1 -b:a 64k -vcodec libx264 -b:v 300k -r 30 -g 30 prueba1.mp4 

At first I had problems with the hw:3 component. Instead, I set it to default and the code actually worked. Hope this helps.

Answer 2

I found that using the command below works for an external USB webcam (my current Logitech C310). I used this command on my laptop, which already has a built-in microphone / webcam, and it still captures audio and video from my C310. Obviously change / dev / video 0 to suit your needs. you can use

 ls /dev/video* 

in the terminal to find out which video capture devices created by your OS.

 ffmpeg -f alsa -i default -itsoffset 00:00:00 -f video4linux2 -s 1280x720 -r 25 -i /dev/video0 out.avi 

Answer 3

This works for high quality video:

 ffmpeg -f alsa -ac 2 -i hw:1,0 -f video4linux2 -i /dev/video0 -acodec ac3 -ab \ 128k -f matroska -s 1280x720 -vcodec libx264 -preset ultrafast -qp 16 testsize.mkv