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• How to improve quality and latency in FFmpeg

  3 August 2020, by Andrew

  I'm trying to stream FFmpeg over the new SRT protocol that's supported as an output. For now though, I'm sending it in the form of FFmpeg -> UDP -> SRT -> SRT -> UDP -> MPV/FFmpeg.

  


  Somewhere along the line, the quality degrades sharply, and latency increases by quite a bit. This seemed to happen when adding audio. Meaning, if streaming just video, quality is decent and latency is low. If streaming just audio, quality is great but latency is high.

  


  Not sure where I'm going wrong with this, so any help would be appreciated. The main focus points is high quality low latency.

  


  ---

  


  Recording video through:

  


  ./ffmpeg.exe -rtbufsize 2147M -f dshow -i video="":audio="" -flush_packets 0 -preset medium -tune zerolatency -f mp4 -b:v 6M -g 30 -f mpegts udp://127.0.0.1:9001?pkt_size=1316


  


  or

  


  ./ffmpeg.exe -f dshow -analyzeduration 200k -probesize 6M -i video="":audio="" -flush_packets 0 -preset fast -tune zerolatency -b:v 5M -b:a 384K -c:a libopus -g 25 -f mpegts udp://127.0.0.1:9001?pkt_size=1316


  


  ---

  


  Then when taking it back at the receiver side, I use one of:

  


  ./ffmpeg.exe -i udp://127.0.0.1:9001 -c copy -bufsize 32M -f mpegts udp://127.0.0.1:9002?bitrate=26214400
./mpv.exe udp://127.0.0.1:9002


  


  or

  


  ./mpv.exe --no-cache --untimed --no-demuxer-thread --video-sync=audio --vd-lavc-threads=1 udp://127.0.0.1:9002


  


  ---

  


  What am I missing? As is quality is generally terrible and latency can get up to 10 seconds. Is it just not possible with this set up?

  


• Merge commit ’715f139c9bd407ef7f4d1f564ad683140ec61e6d’

  23 March 2017, by Clément Bœsch

  Merge commit ’715f139c9bd407ef7f4d1f564ad683140ec61e6d’
  * commit ’715f139c9bd407ef7f4d1f564ad683140ec61e6d’: (23 commits)
  
    vp9lpf/x86: make filter_16_h work on 32-bit.
  
    vp9lpf/x86: make filter_48/84/88_h work on 32-bit.
  
    vp9lpf/x86: make filter_44_h work on 32-bit.
  
    vp9lpf/x86: make filter_16_v work on 32-bit.
  
    vp9lpf/x86: make filter_48/84_v work on 32-bit.
  
    vp9lpf/x86: make filter_88_v work on 32-bit.
  
    vp9lpf/x86: make filter_44_v work on 32-bit.
  
    vp9lpf/x86: save one register in SIGN_ADD/SUB.
  
    vp9lpf/x86: store unpacked intermediates for filter6/14 on stack.
  
    vp9lpf/x86: move variable assigned inside macro branch.
  
    vp9lpf/x86: simplify ABSSUM_CMP by inverting the comparison meaning.
  
    vp9lpf/x86: remove unused register from ABSSUB_CMP macro.
  
    vp9lpf/x86: slightly simplify 44/48/84/88 h stores.
  
    vp9lpf/x86: make cglobal statement more conservative in register allocation.
  
    vp9lpf/x86: save one register in loopfilter surface coverage.
  
    vp9lpf/x86: add ff_vp9_loop_filter_[vh]_44_16_sse2,ssse3,avx.
  
    vp9lpf/x86: add ff_vp9_loop_filter_h_48,84_16_sse2,ssse3,avx().
  
    vp9lpf/x86: add an SSE2 version of vp9_loop_filter_[vh]_88_16
  
    vp9lpf/x86: add ff_vp9_loop_filter_[vh]_88_16_ssse3,avx.
  
    vp9lpf/x86: add ff_vp9_loop_filter_[vh]_16_16_sse2().
  
    ...
  All these commits are cherry-picks from FFmpeg. Maybe some slight
  
  differences sneaked in but the Libav codebase still differs too much
  
  with our own to make a proper diff. This merge is a noop.
  Merged-by: Clément Bœsch <u@pkh.me>
  

• setting bit rates in creating video from images in ffmpeg not working

  2 May 2014, by mast kalandar

  I have a HQ video of one second

  Some information of this video is as below

  Dimensions : 1920 x 1080    
  
  Codec : H.264    
  
  Framerate : 30 frames per second    
  
  Size : 684.7 kB (6,84,673 bytes)
  
  Bitrates : 5458 kbps

  I have extracted frames from video

  ffmpeg -i f1.mp4 f%d.jpg

  All images are of 1920 x 1020 pixels by default 30 frames are generated (f7_1.jpg, f7_2.jpg,.....,f7_30.jpg)

  I have added some texts and objects to these images (without changing dimensions of any image, all 30 images are still of 1920 x 1020 pixels)

  Now I am trying to merge all these images to create single video (of 1 second)

  I referred this official document, I have run below command

  ffmpeg -f image2 -i f7_%d.jpg -r 30 -b:v 5458k foo_5458_2.mp4

  Video created is also of one second, thing is its bit rates are higher then the original one. New video has 6091 kbps bit rates, while I expect are 5458 kbps only.

  Because of higher bits, its gets finish very quickly compare to original video in video player.

  Is there any thing I missing ??

  And I don’t know what is exact meaning and job of -f image2 option, when I run command without this option, I am getting same video.