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• How to map inputs from multiple device into single stream with multiple channels ?

  30 septembre 2019, par ศาสะ ศรีศักดิ์

  I’m try to use ffmpeg to map audio streams from 4 sound cards in to single file with 8 channels. I’m try to learn how to use map_channel or -filter_complex but no luck, its hard to understand. Please tell me how command should be.

  Here is my code so far.

  ffmpeg -f dshow -i audio="Mic/Inst/Line In 1/2 (4- Studio 1824)"
  
  -f dshow -i audio="Mic/Line In 3/4 (4- Studio 1824)"
  
  -f dshow -i audio="Mic/Line In 5/6 (4- Studio 1824)"
  
  -f dshow -i audio="Mic/Line In 7/8 (4- Studio 1824)"
  
  -filter_complex "[0:a:0][0:a:1][1:a:0][1:a:1][2:a:0][2:a:1][3:a:0][3:a:1] amerge=inputs=8" output.wav

  After many trials and errors. some working code.

  ffmpeg -f dshow -i audio="Mic/Inst/Line In 1/2 (4- Studio 1824)"
  
  -f dshow -i audio="Mic/Line In 3/4 (4- Studio 1824)"
  
  -f dshow -i audio="Mic/Line In 5/6 (4- Studio 1824)"
  
  -f dshow -i audio="Mic/Line In 7/8 (4- Studio 1824)"
  
  -filter_complex "[0:a][1:a][2:a][3:a]amerge=inputs=4[a]" -map "[a]" output.wav

  Thought, I still don’t understand what is -map "[a]" do.

• How can I set up ALSA on VDS ?

  30 novembre 2014, par user2794729

  Greetings to everyone.

  I’m trying to convert SWF to MP4 using dump-gnash and ffmpeg.

  But the problem is the dump-gnash won’t create raw video without ALSA set up properly.

  Here is a part of dump-gnash log :

  ALSA lib confmisc.c:768:(parse_card) cannot find card '0'
ALSA lib conf.c:4241:(_snd_config_evaluate) function snd_func_card_driver returned error: No such file or directory
ALSA lib confmisc.c:392:(snd_func_concat) error evaluating strings
ALSA lib conf.c:4241:(_snd_config_evaluate) function snd_func_concat returned error: No such file or directory
ALSA lib confmisc.c:1251:(snd_func_refer) error evaluating name
ALSA lib conf.c:4241:(_snd_config_evaluate) function snd_func_refer returned error: No such file or directory
ALSA lib conf.c:4720:(snd_config_expand) Evaluate error: No such file or directory
ALSA lib pcm.c:2217:(snd_pcm_open_noupdate) Unknown PCM default
Killed

  I readed about ALSA and learned is’t a sound card handler tool.

  But I don’t have any sound cards on my VDS. Then there is a question : how can i set up ALSA on VDS and make it work ?

• FFmpeg : H.265/HEVC - does not work on Sony Smart-TV if you change encoder

  25 juillet 2019, par oigen90

  We have such Sony Bravia Smart-TV devices :

  • Sony KD-49XD7005 (2016) - Android
  • Sony KD-49XE7096 (2017) - Linux

  Those devices does have HEVC support, as well as 4K support.

  Also, we have a one minute Apple ProRes 4K video file. I need to transcode it into HEVC with some simple params, create DASH manifest and stream it into HTML5-player.
  The problem is that if I use the regular ’libx265’ codec passing it after "-c:v" - the video does not play on Sony Bravia (just freezes on ’loadstart’ player’s event). But if I use ’hevc_nvenc’ - it works ! What’s the reason of such behavior ? Both of codecs should work identically, hevc_nvenc just should be faster and was made to work on nvidia graphic cards (that’s all I know about those codecs’ difference so far). But in fact we have working stream encoded into hevc_nvenc and invalid stream encoded into libx265.

  See my FFmpeg command below.

  Which thoughts do you have ? If you want me to provide some more info - feel free to ask.

  ffmpeg -i input.mov -c:v hevc_nvenc -pix_fmt yuv420p -b:v 12000k -maxrate 14000k -bufsize 6000k -c:a copy -f mp4 output.mp4