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• Live video encoding using...?

  27 décembre 2013, par Basic

  I'm attempting to write a fairly simplistic application that will stream video/audio from a webcam to someone else across the internet (ala Skypebut with more control).

  There seems to be very little useful/relevant information on the subjectand what I can find is largely outdated. From my research so far, x264 seems to be the way to go as it offers an ultrafast option which is designed for this situation

  I'm able to turn on the webcam and receive a stream of images. I can also listen on an audio device and get samples.

  Where I'm failing is encoding that information in such a way as to be able to stream with a minimum of latency (from what I've read, 200ms delay is the goal for no obvious lag, including network latency - so let's aim for 100-150ms)

  Things I've tried

  ffmpeg

  This seems to be the most widely used option for encoding. I've had two real issues using it. Firstly, even using x264 with no look-aheads and the bare minimum buffers for stability, the delay seems to be on the order of 700ms using image2pipe. Secondly, it requires ffmpeg to be installed - being able to do this without an external dependency would be nice.

  VLC

  As with ffmpeg this requires an external program which is a negative. Even worse, I can't seem to get a latency of under 2 seconds which seems to increase over time. I've also only been able to get VLC to capture the camera itself rather than take a stream of images which means I don't get a chance to pre-process them.

  DirectShow

  I've seen a number of sites recommending using the windows direct show encoders but I haven't been able to find one that works at anything like real time. In fact, the only one I've managed to get going reliably is a Windows Media codec that has a massive latency and fairly large size.

  Other considerations

  None of the above address the problem of adding an audio stream to the video. I'm not sure if I should attempt to encode them together or send a separate stream alongside the video.

  In short, I've been Googling for a week or so now and haven't found a decent way to do this. Can someone please point me at a decent example/guide ?

• Make mime-type award a bonus probe score

  21 novembre 2023, par Peter Zebühr

  Make mime-type award a bonus probe score
  This changes the default behaviour of ffmpeg where content-type headers
  
  on an input gives an absolut probe score (of 75) to instead give a bonus
  
  score (of 30). This gives the probe a better chance to arrive at the
  
  correct format by (hopefully) giving a large enough bonus to push edge
  
  cases in the right direction (MPEG-PS vs MP3, I am looking at you) while
  
  also not adversly punishing clearer cases (raw ADTS marked as
  
  "audio/mpeg" for example).
  This patch was regression tested against 20 million recent podcast
  
  submissions (after content-type propagation was added to
  
  original-storage), and 50k Juno vodcasts submissions (dito). No adverse
  
  effects observed (but the bonus may still need tweaking if other edge
  
  cases are detected in production).
  

  • [DH] libavformat/avformat.h
  • [DH] libavformat/format.c
  • [DH] libavformat/libopenmpt.c

• How to get ffmpeg to output hls with multiple resolutions ? [closed]

  23 septembre 2022, par CamHart

  I'm trying to switch my ffmpeg command from outputting a single mp4 to outputting hls files for 1080p, 2k, and 4k.

  


  Here's the mp4 command that currently works :
  
ffmpeg.exe -y -framerate 50 -i 1.%09d.jpg.blurred.png -framerate 50 -i 2.%09d.jpg.blurred.png -i input.mp4  -filter_complex "[0:v]v360=equirect:equirect:yaw=180 [s1],[1:v]v360=equirect:equirect:yaw=90 [s2],[s1][s2]overlay [ovr1],[ovr1]scale=3840:1920 [ovr2],[2:v]scale=3840:1920 [ovr3],[ovr3][ovr2]overlay" -c:v libx264 -crf 17 -r 50 -profile:v high -level 5.1 -pix_fmt yuv420p -preset faster -g 100 -movflags faststart -c:a copy output.mp4


  


  I've tinkered around over and over again, but I can't seem to get it to work. I'm still quite confused by -map and -var_stream_map. Here's what I have currently :


  
ffmpeg.exe -y -framerate 50 -i 1.%09d.jpg.blurred.png -framerate 50 -i 2.%09d.jpg.blurred.png -i input.mp4 -filter_complex "[0:v]v360=equirect:equirect:yaw=180 [s1],[1:v]v360=equirect:equirect:yaw=90 [s2],[s1][s2]overlay [ovr1],[ovr1]scale=3840:1920 [ovr2],[2:v]scale=3840:1920 [ovr3],[ovr3][ovr2]overlay [src],[src]split=2[v1][v2],[v1]scale=1920x1080 [v1out],[v2]scale=2560x1440 [v2out]" -map [v1out] -c:v:0 libx264 -crf 17 -r 50 -preset veryfast -g 100 -sc_threshold 0 -keyint_min 100 -map [v2out] -c:v:0 libx264 -crf 17 -r 50 -preset veryfast -g 100 -sc_threshold 0 -keyint_min 100 -map [src] -c:v:0 libx264 -crf 17 -r 50 -preset veryfast -g 100 -sc_threshold 0 -keyint_min 100 -map 2:a:0 -c copy -f hls -hls_time 2 -hls_playlist_type vod -hls_flags independent_segments -hls_segment_type mpegts -hls_segment_filename stream_%v/data%02d.ts -master_pl_name master.m3u8 -var_stream_map “v:0,a:0 v:1,a:0 v:2,a:0” stream_%v/stream.m3u8


  


  Any chance anyone can help me out ? Basically I need to take "src" (the stream named that in the command) and produce hls output for it at 1080p, 2k, 4k resolutions.