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• How can I capture audio AND video simultenaous with ffmpeg from a linux USB capture device

  7 juin 2019, par oban

  I’m capturing a video by means of an USB Terratec Grabster AV350 (which is based on the em2860 chip).

  I don’t succeed to get the audio when it is played . If I play the captured video with vlc or with ffplay I got only 3 seconds sound and then a silence for the rest of the video ...

  During the capturing I don’t get any errors. At the end it indicates the size of the video and audio captured ....

  I’m using 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

  The log is :

  [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 for only capturing audio, then the audio 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 for only video capturing then vlc or ffplay can play the video successfully :

  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%

  Strange behaviour I noticed is that when I tried capturing video and audio, I can not capture the audio afterwards any more,
  unless I unplug the AV350 first.

  The G350 is located at card 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

  The OS is a Linux 2.6.38-8-generic with the Ubuntu Natty Narwhal version

  Any help on how to tackle this issue would be great ....

  Thanks !

• Play mpeg-2 file with 608/708 embedded captions out Decklink SDI

  29 octobre 2022, par asperi

  I have built ffmpeg with decklink support, it plays my mpg file fine out the SDI but not seeing any captions on my works broadcast monitor (JVC DT-V17G1Z). This monitor shows captions on SDI from my Mojito card but trying to get it to work with a BlackMagic 4k extreme. The mpg file has embedded 608 and 708 captions. Using the to play-

  


  ffmpeg -i C:\video\RD2838_720p.mpg -f decklink -pix_fmt uyvy422 "DeckLink 4K Extreme"


  


  MediaInfo on captinos :

  


  Text #1


  


  ID : 4096 (0x1000)-CC1
Menu ID : 1 (0x1)
Format : EIA-608
Muxing mode : A/53 / DTVCC Transport
Muxing mode, more info : Muxed in Video #1
Duration : 28 min 30 s
Bit rate mode : Constant
Stream size : 0.00 Byte (0%)
Language : English
CaptionServiceName : CC1

  


  Text #2
ID : 4096 (0x1000)-1
Menu ID : 1 (0x1)
Format : EIA-708
Muxing mode : A/53 / DTVCC Transport
Muxing mode, more info : Muxed in Video #1
Duration : 28 min 30 s
Bit rate mode : Constant
Stream size : 0.00 Byte (0%)
Language : English

  


  How do I get the Decklink 4k to pass the captions ? Thanks !

  


• How use FFMPEG multi GPU proccess

  31 janvier 2021, par R.A.M

  
I have a problem and cant find any suitable answer for it.
  
Its about use multi GPU proccess.
  
I have 3 graphic card and you could see it :

  
[![enter image description here][1]][1]


  if image not loaded use this image link : https://i.stack.imgur.com/msR83.jpg enter link description here

  

  
My problem is : when i run more than one ffmpeg command with cuda all process assigned to first GPU.
  
like below image :

  
[![enter image description here][2]][2]


  if image not loaded use this image link : https://i.stack.imgur.com/PfYfz.jpg

  


  you see ? all 6 proccess assigned to first GPU.
  
I really confused how could i fix it.
  

  
my FFMPEG code is :
  

  


  ffmpeg -y -vsync 0 -hwaccel cuda -hwaccel_output_format cuda -i my-video.mp4 \
  -vf scale_npp=w=426:h=240 -c:v h264_nvenc -profile:v main -b:v 400k -sc_threshold 0 -g 25 \
  -c:a aac -b:a 64k -ar 48000 \
  -f hls -hls_time 6 -hls_playlist_type vod \
  -hls_allow_cache 1 -hls_key_info_file encription.keyinfo \
  -hls_segment_filename f-0-seg-%d.ts f-0.m3u8


  


  i run top FFMPEG code for 6 diffrent video at same time.
  
please help to find answer. by sharing your knowledge or some links that could help me.
  
Thanks a lot.