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• x86/tx_float : implement inverse MDCT AVX2 assembly

  3 septembre 2022, par Lynne

  x86/tx_float : implement inverse MDCT AVX2 assembly
  This commit implements an iMDCT in pure assembly.
  This is capable of processing any mod-8 transforms, rather than just
  
  power of two, but since power of two is all we have assembly for
  
  currently, that's what's supported.
  
  It would really benefit if we could somehow use the C code to decide
  
  which function to jump into, but exposing function labels from assebly
  
  into C is anything but easy.
  
  The post-transform loop could probably be improved.
  This was somewhat annoying to write, as we must support arbitrary
  
  strides during runtime. There's a fast branch for stride == 4 bytes
  
  and a slower one which uses vgatherdps.
  Zen 3 benchmarks for stride == 4 for old (av_imdct_half) vs new (av_tx) :
  128pt :
  
     2811 decicycles in         av_tx (imdct),16775916 runs,   1300 skips
  
     3082 decicycles in         av_imdct_half,16776751 runs,    465 skips
  256pt :
  
     4920 decicycles in         av_tx (imdct),16775820 runs,   1396 skips
  
     5378 decicycles in         av_imdct_half,16776411 runs,    805 skips
  512pt :
  
     9668 decicycles in         av_tx (imdct),16775774 runs,   1442 skips
  
    10626 decicycles in         av_imdct_half,16775647 runs,   1569 skips
  1024pt :
  
    19812 decicycles in         av_tx (imdct),16777144 runs,     72 skips
  
    23036 decicycles in         av_imdct_half,16777167 runs,     49 skips
  

  • [DH] libavutil/tx.c
  • [DH] libavutil/tx_priv.h
  • [DH] libavutil/x86/tx_float.asm
  • [DH] libavutil/x86/tx_float_init.c

• Is there a way to add/modify/delete one of the outputs of a running ffmpeg core which has multiple ones ?

  7 novembre 2022, par Edward Sternin

  The task is to stream a video feed from a webcam, watch it live on a display, then start/stop a recording of same into a file, while maintaining the live video feed.

  


  This will record a 5-s clip (with no audio), while simultaneously watching it on the screen :

  


  ffmpeg -v error -f v4l2 -framerate 30 -video_size 640x480 -t 5 -i /dev/video0 -an \
    clip.mp4 -y -map 0:v -pix_fmt yuv420p -f xv "Capturing a 5-s clip" 


  


  however I need to surround it before and after with live display :

  


  ffmpeg -v error -f v4l2 -framerate 30 -video_size 640x480 -i /dev/video0 -an \ 
    -map 0:v -pix_fmt yuv420p -f xv "Live display"


  


  which I then kill in order to launch the recording version and re-launch when that one terminates. This creates a noticeable break as one ffmpeg dies and another launches.

  


  This explains how to pause/resume ffmpeg process itself using
kill -s SIGSTOP <pid></pid> and kill -s SIGCONT <pid></pid> as needed, but what I want is to pause/resume (or start/stop) just the recording output, while keeping the display output continuous.

  


  Another way to think about it is whether it is possible to add an extra output stream to a running ffmpeg core, and either pass a time restriction to it - so it disconnects itself when done, or have an ability to delete an output from a running ffmpeg core, without killing the other outputs.

  


• FFMPEG RTSP stream to multiple output, one mp4 and also restream

  16 août 2022, par csonty

  I would like to seek your help with FFMPEG and how to use it properly on Windows and Linux. I have to get the camera RTSP stream and record it into 1 minutes segments and also stream at the same time.
I did try to stream it to rtsp, but it didn't work at all [f=RTSP]rtsp ://ipaddress:554/mystream , it stuck and did nothing.

  


  I did also try to add the -use_wallclock_as_timestamps 1 but it didn't do anything. I also tried to add the -flags +global_header, but not sure, how to add it into this script.

  


  I did try it on both Linux and Windows with the following commands (not sure how to create a bash script from it)

  


  Linux :
./usr/bin/ffmpeg -i 'rtsp://username:password@192.168.68.99:554/Streaming/Channels/101/' -c copy -f tee -map 0:v '[f=segment:strftime=1:segment_time=60]wwcam99-%Y-%m-%d_%H-%M-%S.mp4|[f=mpegts]udp://10.10.3.251:5555'

  


  Windows :
ffmpeg -i "rtsp://username:password@192.168.68.99:554/Streaming/Channels/101/" -c copy -f tee -map 0:v "[f=segment:strftime=1:segment_time=60]wwcam99-%%Y-%%m-%%d_%%H-%%M-%%S.mp4|[f=mpegts]udp://10.10.3.199:5555"

  


  It records the files and the stream can be viewed on the localhost (not sure why I cannot view from other machines even if the firewall is off, but it might be a network issue)

  


  This is the output with mostly error messages that I couldn't fix :

  


  


  [rtsp @ 0x563f2688cf80] max delay reached. need to consume packet
[rtsp @ 0x563f2688cf80] RTP : missed 216 packets
[h264 @ 0x563f26890c40] left block unavailable for requested intra4x4 mode -1
[h264 @ 0x563f26890c40] error while decoding MB 0 12, bytestream 144004
[h264 @ 0x563f26890c40] concealing 13993 DC, 13993 AC, 13993 MV errors in I frame
Input #0, rtsp, from 'rtsp ://username:password@192.168.68.99:554/Streaming/Channels/101/' :
Metadata :
title : Media Presentation
Duration : N/A, start : 0.983333, bitrate : N/A
Stream #0:0 : Video : h264 (Main), yuvj420p(pc, bt709, progressive), 2688x1520 [SAR 1:1 DAR 168:95], 6 fps, 20 tbr, 90k tbn, 12 tbc
[segment @ 0x563f268ced00] Opening 'wwcam99-2022-08-16_17-28-20.mp4' for writing
Output #0, tee, to '[f=segment:strftime=1:segment_time=60]wwcam09-%Y-%m-%d_%H-%M-%S.mp4|[f=mpegts]udp ://10.10.3.251:5555' :
Metadata :
title : Media Presentation
encoder : Lavf58.29.100
Stream #0:0 : Video : h264 (Main), yuvj420p(pc, bt709, progressive), 2688x1520 [SAR 1:1 DAR 168:95], q=2-31, 6 fps, 20 tbr, 6 tbn, 6 tbc
Stream mapping :
Stream #0:0 -> #0:0 (copy)
Press [q] to stop, [?] for help
[tee @ 0x563f268cbc00] Non-monotonous DTS in output stream 0:0 ; previous : 0, current : -5 ; changing to 1. This may result in incorrect timestamps in the output file.
[tee @ 0x563f268cbc00] Non-monotonous DTS in output stream 0:0 ; previous : 1, current : -4 ; changing to 2. This may result in incorrect timestamps in the output file.
[tee @ 0x563f268cbc00] Non-monotonous DTS in output stream 0:0 ; previous : 2, current : -3 ; changing to 3. This may result in incorrect timestamps in the output file.
[tee @ 0x563f268cbc00] Non-monotonous DTS in output stream 0:0 ; previous : 3, current : -2 ; changing to 4. This may result in incorrect timestamps in the output file.
[tee @ 0x563f268cbc00] Non-monotonous DTS in output stream 0:0 ; previous : 4, current : -1 ; changing to 5. This may result in incorrect timestamps in the output file.
[tee @ 0x563f268cbc00] Non-monotonous DTS in output stream 0:0 ; previous : 5, current : 0 ; changing to 6. This may result in incorrect timestamps in the output file.
[tee @ 0x563f268cbc00] Non-monotonous DTS in output stream 0:0 ; previous : 6, current : 1 ; changing to 7. This may result in incorrect timestamps in the output file.
[tee @ 0x563f268cbc00] Non-monotonous DTS in output stream 0:0 ; previous : 7, current : 2 ; changing to 8. This may result in incorrect timestamps in the output file.
[tee @ 0x563f268cbc00] Non-monotonous DTS in output stream 0:0 ; previous : 8, current : 3 ; changing to 9. This may result in incorrect timestamps in the output file.
[tee @ 0x563f268cbc00] Non-monotonous DTS in output stream 0:0 ; previous : 9, current : 4 ; changing to 10. This may result in incorrect timestamps in the output file.

  


  


  Any help would be highly appreciated