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• Latency and DAF in RTP transmissions

  24 février 2023, par jfernandz

  I'm trying to perform some tests for audio RTP transmissions to know their technical limitations. The idea is to prevent DAF effect in this kind of transmissions, I'm assuming a latency lower than 50ms will prevent it. But there is another handicap in my analysis, the RTP transmission must be over WiFi.

  


  For this tests I'm trying to transmit raw audio (not sure if skipping the encoding stage will improve latency) through ffmpeg between two different laptops, so I'm running ffmpeg in the first laptop (172.20.1.2) as :

  


  $ ffmpeg -f pulse -i 56 -c copy -f rtp rtp://172.20.1.5:10000

  


  which produces the following output :

  


  ffmpeg version n5.1.2 Copyright (c) 2000-2022 the FFmpeg developers
  built with gcc 12.2.0 (GCC)
  configuration: --prefix=/usr --disable-debug --disable-static --disable-stripping --enable-amf --enable-avisynth --enable-cuda-llvm --enable-lto --enable-fontconfig --enable-gmp --enable-gnutls --enable-gpl --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libbs2b --enable-libdav1d --enable-libdrm --enable-libfreetype --enable-libfribidi --enable-libgsm --enable-libiec61883 --enable-libjack --enable-libmfx --enable-libmodplug --enable-libmp3lame --enable-libopencore_amrnb --enable-libopencore_amrwb --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-librav1e --enable-librsvg --enable-libsoxr --enable-libspeex --enable-libsrt --enable-libssh --enable-libsvtav1 --enable-libtheora --enable-libv4l2 --enable-libvidstab --enable-libvmaf --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxcb --enable-libxml2 --enable-libxvid --enable-libzimg --enable-nvdec --enable-nvenc --enable-opencl --enable-opengl --enable-shared --enable-version3 --enable-vulkan
  libavutil      57. 28.100 / 57. 28.100
  libavcodec     59. 37.100 / 59. 37.100
  libavformat    59. 27.100 / 59. 27.100
  libavdevice    59.  7.100 / 59.  7.100
  libavfilter     8. 44.100 /  8. 44.100
  libswscale      6.  7.100 /  6.  7.100
  libswresample   4.  7.100 /  4.  7.100
  libpostproc    56.  6.100 / 56.  6.100
Guessed Channel Layout for Input Stream #0.0 : stereo
Input #0, pulse, from '56':
  Duration: N/A, start: 1677234050.938677, bitrate: 1536 kb/s
  Stream #0:0: Audio: pcm_s16le, 48000 Hz, stereo, s16, 1536 kb/s
Output #0, rtp, to 'rtp://172.20.1.5:10000':
  Metadata:
    encoder         : Lavf59.27.100
  Stream #0:0: Audio: pcm_s16le, 48000 Hz, stereo, s16, 1536 kb/s
SDP:
v=0
o=- 0 0 IN IP4 127.0.0.1
s=No Name
c=IN IP4 172.20.1.5
t=0 0
a=tool:libavformat LIBAVFORMAT_VERSION
m=audio 10000 RTP/AVP 97
b=AS:1536

Stream mapping:
  Stream #0:0 -> #0:0 (copy)
Press [q] to stop, [?] for help
size=     322kB time=00:00:01.67 bitrate=1573.6kbits/s speed=1.06x


  


  I'm assuming the shown SDP is a valid one :

  


  v=0
o=- 0 0 IN IP4 127.0.0.1
s=No Name
c=IN IP4 172.20.1.5
t=0 0
a=tool:libavformat LIBAVFORMAT_VERSION
m=audio 10000 RTP/AVP 97
b=AS:1536


  


  So I saved it in a file called ccopy.sdp on the second laptop (172.20.1.5). However, when I run ffplay in this other laptop as :

  


  $ ffplay -protocol_whitelist file,rtp,udp -i ccopy.sdp

  


  I can see there is problems with this SDP :

  


  ffplay version n5.1.2 Copyright (c) 2003-2022 the FFmpeg developers
  built with gcc 12.2.0 (GCC)
  configuration: --prefix=/usr --disable-debug --disable-static --disable-stripping --enable-amf --enable-avisynth --enable-cuda-llvm --enable-lto --enable-fontconfig --enable-gmp --enable-gnutls --enable-gpl --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libbs2b --enable-libdav1d --enable-libdrm --enable-libfreetype --enable-libfribidi --enable-libgsm --enable-libiec61883 --enable-libjack --enable-libmfx --enable-libmodplug --enable-libmp3lame --enable-libopencore_amrnb --enable-libopencore_amrwb --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-librav1e --enable-librsvg --enable-libsoxr --enable-libspeex --enable-libsrt --enable-libssh --enable-libsvtav1 --enable-libtheora --enable-libv4l2 --enable-libvidstab --enable-libvmaf --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxcb --enable-libxml2 --enable-libxvid --enable-libzimg --enable-nvdec --enable-nvenc --enable-opencl --enable-opengl --enable-shared --enable-version3 --enable-vulkan
  libavutil      57. 28.100 / 57. 28.100
  libavcodec     59. 37.100 / 59. 37.100
  libavformat    59. 27.100 / 59. 27.100
  libavdevice    59.  7.100 / 59.  7.100
  libavfilter     8. 44.100 /  8. 44.100
  libswscale      6.  7.100 /  6.  7.100
  libswresample   4.  7.100 /  4.  7.100
  libpostproc    56.  6.100 / 56.  6.100
[sdp @ 0x7f8eec000c80] Could not find codec parameters for stream 0 (Audio: none, 0 channels): unknown codec
Consider increasing the value for the 'analyzeduration' (0) and 'probesize' (5000000) options
Input #0, sdp, from 'ccopy.sdp':
  Metadata:
    title           : No Name
  Duration: N/A, bitrate: N/A
  Stream #0:0: Audio: none, 0 channels
Failed to open file 'ccopy.sdp' or configure filtergraph
    nan    :  0.000 fd=   0 aq=    0KB vq=    0KB sq=    0B f=0/0   


  


  Not sure if I'm doing something wrong or this is because of I cannot actually use pcm_s16le for an RTP transmission. Moreover ... Is there some argument for ffmpeg that I can use to improve this RTP transmission and reduce latency under 50ms.

  


  Thank you all :-)

  


  PS : When I don't use -c copy argument for ffmpeg and therefore I have this SDP

  


  v=0
o=- 0 0 IN IP4 127.0.0.1
s=No Name
c=IN IP4 172.20.1.5
t=0 0
a=tool:libavformat LIBAVFORMAT_VERSION
m=audio 10000 RTP/AVP 97
b=AS:768
a=rtpmap:97 PCMU/48000/2


  


  The RTP transmission works as I expect, but with a significant DAF.

  


• ffmpeg - when cutting video, last frame is green [on hold]

  4 juillet 2016, par Mister Fresh

  In a php web app, the user can upload a video and cut it in samples. Php launches a shell command with shell_exec() to start ffmpeg and cut the video.

  It works except that the last frame shows a green splash in the cut sample.

  Server is on linux. In dev environment (mac) with latest ffmpeg, the problem cannot be reproduced.

  Command is the following :

  ffmpeg -i /var/www/user_dir/web/projects/127472/cuts/1146 -ss 00:00:45 -t 15 -vcodec libx264 -s 640x360 -strict experimental -v quiet -y /var/www/user_dir/web/projects/127472/cuts/sample1954_small.mp4

  Console output :

  ffmpeg version 0.8.17-6:0.8.17-1, 
  
  
  
  Copyright (c) 2000-2014 the Libav developers
  
  
  
  built on Mar 15 2015 17:00:31 with gcc 4.7.2
  
  
  
  configuration: --arch=amd64 --enable-pthreads --enable-runtime-cpudetect --extra-version='6:0.8.17-1' --libdir=/usr/lib/x86_64-linux-gnu --prefix=/usr --enable-bzlib --enable-libdc1394 --enable-libdirac --enable-libfreetype --enable-frei0r --enable-gnutls --enable-libgsm --enable-libmp3lame --enable-librtmp --enable-libopencv --enable-libopenjpeg --enable-libpulse --enable-libschroedinger --enable-libspeex --enable-libtheora --enable-vaapi --enable-vdpau --enable-libvorbis --enable-libvpx --enable-zlib --enable-gpl --enable-postproc --enable-swscale --enable-libcdio --enable-x11grab --enable-libx264 --enable-libxvid --shlibdir=/usr/lib/x86_64-linux-gnu --enable-shared --disable-static
  
  
  
  libavutil    51. 22. 3 / 51. 22. 3
  
  
  
  libavcodec   53. 35. 0 / 53. 35. 0
  
  
  
  libavformat  53. 21. 1 / 53. 21. 1
  
  
  
  libavdevice  53.  2. 0 / 53.  2. 0
  
  
  
  libavfilter   2. 15. 0 /  2. 15. 0
  
  
  
  libswscale    2.  1. 0 /  2.  1. 0
  
  
  
  libpostproc  52.  0. 0 / 52.  0. 0
  
  
  
  The ffmpeg program is only provided for script compatibility and will be removed
  
  in a future release. It has been deprecated in the Libav project to allow for
  
  incompatible command line syntax improvements in its replacement called avconv
  
  (see Changelog for details). Please use avconv instead.
  
  
  
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/var/www/user_dir/web/projects/127472/cuts/1146':
  
  
  
  Metadata:
  
      major_brand     : isom
  
      minor_version   : 512
  
      compatible_brands: isomiso2avc1mp41
  
      encoder         : Lavf56.15.103
  
      genre           : Blues
  
  
  
  Duration: 00:01:29.47, start: 0.036281, bitrate: 808 kb/s
  
  
  
  Stream #0.0(und): Video: h264 (High), yuv420p, 1920x1080 [PAR 1:1 DAR 16:9], 675 kb/s, 25 fps, 25 tbr, 12800 tbn, 50 tbc
  
  
  
  Stream #0.1(und): Audio: aac, 44100 Hz, stereo, s16, 128 kb/s
  
  [buffer @ 0x30a2ca0] w:1920 h:1080 pixfmt:yuv420p
  
  [scale @ 0x309bf00] w:1920 h:1080 fmt:yuv420p -> w:640 h:360 fmt:yuv420p flags:0x4
  
  [libx264 @ 0x30a3200] using SAR=1/1
  
  [libx264 @ 0x30a3200] using cpu capabilities: MMX2 SSE2Fast SSSE3 FastShuffle SSE4.2
  
  [libx264 @ 0x30a3200] profile Main, level 3.0
  
  [libx264 @ 0x30a3200] 264 - core 123 r2189 35cf912 - H.264/MPEG-4 AVC codec - 
  
  
  
      Copyleft 2003-2012 - http://www.videolan.org/x264.html 
  
  - options: cabac=1 ref=3 deblock=1:0:0 analyse=0x1:0x111 me=hex subme=7 psy=1 psy_rd=1.00:0.00 mixed_ref=0 me_range=16 chroma_me=1 trellis=1 8x8dct=0 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=-2 threads=1 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=3 b_pyramid=0 b_adapt=1 b_bias=0 direct=1 weightb=0 open_gop=1 weightp=2 keyint=250 keyint_min=25 scenecut=40 intra_refresh=0 rc_lookahead=40 rc=crf mbtree=1 crf=23.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.25 aq=1:1.00
  
  
  
  Output #0, mp4, to '/var/www/user_dir/web/projects/127472/cuts/sample1954_small.mp4':
  
  
  
  Metadata:
  
      major_brand     : isom
  
      minor_version   : 512
  
      compatible_brands: isomiso2avc1mp41
  
      genre           : Blues
  
      encoder         : Lavf53.21.1
  
  
  
  Stream #0.0(und): Video: libx264, yuv420p, 640x360 [PAR 1:1 DAR 16:9], q=-1--1, 25 tbn, 25 tbc
  
  
  
  Stream #0.1(und): Audio: aac, 44100 Hz, stereo, s16, 200 kb/s
  
  Stream mapping:
  
    Stream #0.0 -> #0.0
  
    Stream #0.1 -> #0.1
  
  
  
  Press ctrl-c to stop encoding
  
  
  
  [buffer @ 0x30a2ca0] Buffering several frames is not supported. Please consume all available frames before adding a new one.
  
  
  
  Last message repeated 1124 times 565kB time=12.80 bitrate= 361.7kbits/s    ts/s    
  
  frame=  375 fps= 17 q=28.0 Lsize=     742kB time=14.96 bitrate= 406.4kbits/s    
  
  video:360kB audio:371kB global headers:0kB muxing overhead 1.515374%
  
  frame I:3     Avg QP:16.97  size:  6922
  
  
  
  [libx264 @ 0x30a3200] frame P:158   Avg QP:24.40  size:  1858
  
  
  
  [libx264 @ 0x30a3200] frame B:214   Avg QP:28.69  size:   253
  
  
  
  [libx264 @ 0x30a3200] consecutive B-frames: 13.9% 28.3%  5.6% 52.3%
  
  
  
  [libx264 @ 0x30a3200] mb I  I16..4: 70.8%  0.0% 29.2%
  
  
  
  [libx264 @ 0x30a3200] mb P  I16..4:  4.8%  0.0%  1.6%  P16..4: 16.0%  3.9%  2.0%  0.0%  0.0%    skip:71.9%
  
  
  
  [libx264 @ 0x30a3200] mb B  I16..4:  0.5%  0.0%  0.1%  B16..8: 11.1%  0.7%  0.1%  direct: 0.1%  skip:87.4%  L0:44.2% L1:44.7% BI:11.1%
  
  
  
  [libx264 @ 0x30a3200] coded y,uvDC,uvAC intra: 19.3% 30.9% 23.5% inter: 2.3% 2.3% 1.3%
  
  
  
  [libx264 @ 0x30a3200] i16 v,h,dc,p: 39% 47%  2% 12%
  
  
  
  [libx264 @ 0x30a3200] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 20% 25% 32%  5%  5%  3%  4%  3%  3%
  
  
  
  [libx264 @ 0x30a3200] i8c dc,h,v,p: 51% 40%  7%  2%
  
  
  
  [libx264 @ 0x30a3200] Weighted P-Frames: Y:0.0% UV:0.0%
  
  
  
  [libx264 @ 0x30a3200] ref P L0: 63.7%  4.9% 19.3% 12.1%
  
  
  
  [libx264 @ 0x30a3200] ref B L0: 67.6% 32.4%
  
  
  
  [libx264 @ 0x30a3200] kb/s:196.48

• ffmpeg - zero file size for specific videos ?

  27 mai 2022, par Annabelle

  I am trying the below command for the video conversion

  


  ffmpeg -i " + video_file_path + " -max_muxing_queue_size 21512512 -vf scale=iw*2:ih*2 -preset slow -crf 28 " + path_to_store_generated_width

  


  This is error log

  


  error: Command failed: ffmpeg -i ../uploads/feeds/feeds_e8dc4081b13434b45189a720b77b68181653655030206.mp4 -max_muxing_queue_size21512512 -vf scale=iw*2:ih*2 -preset slow -crf 28 ../uploads/feeds/feed_video_e8dc4081b13434b45189a720b77b68181653655038559.mp4
ffmpeg version 3.4.8 Copyright (c) 2000-2020 the FFmpeg developers
  built with gcc 4.8.5 (GCC) 20150623 (Red Hat 4.8.5-39)
  configuration: --prefix=/usr --bindir=/usr/bin --datadir=/usr/share/ffmpeg --docdir=/usr/share/doc/ffmpeg --incdir=/usr/include/ffmpeg --libdir=/usr/lib64 --mandir=/usr/share/man --arch=x86_64 --optflags='-O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong --param=ssp-buffer-size=4 -grecord-gcc-switches -m64 -mtune=generic' --extra-ldflags='-Wl,-z,relro ' --extra-cflags=' ' --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libvo-amrwbenc --enable-version3 --enable-bzlib --disable-crystalhd --enable-fontconfig --enable-gcrypt --enable-gnutls --enable-ladspa --enable-libass --enable-libbluray --enable-libcdio --enable-libdrm --enable-indev=jack --enable-libfreetype --enable-libfribidi --enable-libgsm --enable-libmp3lame --enable-nvenc --enable-openal --enable-opencl--enable-opengl --enable-libopenjpeg --enable-libopus --disable-encoder=libopus --enable-libpulse --enable-librsvg --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libvorbis --enable-libv4l2 --enable-libvidstab --enable-libvpx --enable-libx264 --enable-libx265 --enable-libxvid --enable-libzvbi --enable-avfilter --enable-avresample --enable-libmodplug --enable-postproc --enable-pthreads --disable-static --enable-shared --enable-gpl --disable-debug --disable-stripping --shlibdir=/usr/lib64 --enable-libmfx --enable-runtime-cpudetect

Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '../uploads/feeds/feeds_e8dc4081b13434b45189a720b77b68181653655030206.mp4':
  Metadata:
    major_brand     : mp42
    minor_version   : 0
    compatible_brands: mp42isom
  Duration: 00:00:20.20, start: 0.000000, bitrate: 807 kb/s
    Stream #0:0(und): Video: h264 (Main) (avc1 / 0x31637661), yuv420p(tv, bt470bg/bt470bg/smpte170m), 640x1138, 746 kb/s, 30 fps, 30 tbr, 15360 tbn, 60 tbc (default)
    Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 64 kb/s (default)
Stream mapping:
  Stream #0:0 -> #0:0 (h264 (native) -> h264 (libx264))
  Stream #0:1 -> #0:1 (aac (native) -> aac (native))
Press [q] to stop, [?] for help
[libx264 @ 0xd61bc0] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX FMA3 AVX2 LZCNT BMI2
[libx264 @ 0xd61bc0] profile High, level 5.0
[libx264 @ 0xd61bc0] 264 - core 148 r2795 aaa9aa8 - H.264/MPEG-4 AVC codec - Copyleft 2003-2017 - http://www.videolan.org/x264.html - options: cabac=1 ref=5 deblock=1:0:0 analyse=0x3:0x113 me=hex subme=8 psy=1 psy_rd=1.00:0.00 mixed_ref=1 me_range=16 chroma_me=1 trellis=2 8x8dct=1 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=-2 threads=48 lookahead_threads=8 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=3 b_pyramid=2 b_adapt=1 b_bias=0 direct=3 weightb=1 open_gop=0 weightp=2 keyint=250 keyint_min=25 scenecut=40 intra_refresh=0 rc_lookahead=50 rc=crf mbtree=1 crf=28.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00
Output #0, mp4, to '../uploads/feeds/feed_video_e8dc4081b13434b45189a720b77b68181653655038559.mp4':
  Metadata:
    major_brand     : mp42
    minor_version   : 0
    compatible_brands: mp42isom
    encoder         : Lavf57.83.100
    Stream #0:0(und): Video: h264 (libx264) (avc1 / 0x31637661), yuv420p, 1280x2276, q=-1--1, 30 fps, 15360 tbn, 30 tbc (default)
    Metadata:
      encoder         : Lavc57.107.100 libx264
    Side data:
      cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: -1
    Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 128 kb/s (default)
    Metadata:
      encoder         : Lavc57.107.100 aac
x264 [error]: malloc of size 9600192 failedime=00:00:02.20 bitrate=   0.0kbits/s dup=2 drop=0 speed=1.71x    1.84x
Video encoding failed
[aac @ 0xcdc7e0] Qavg: 3044.613
[aac @ 0xcdc7e0] 2 frames left in the queue on closing
Conversion failed!


  


  Getting this error for specific videos tried adding crf 0/22 but couldn't work through
I am not familiar with FFmpeg and its usage
Suggestion would be helpful
Thank you !