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• M4a (mp4) audio file encoded with pydub+ffmpeg doesn't play on Android

  6 juillet 2020, par Evelyn

  I have a python script to split up some wav files and export to m4a using pydub. I'm able to get these files to play on several devices, but not on an Android device (using Google Pixel 3). When I try encoding with straight ffmpeg in terminal, that works fine on the Android device.

  


  What is the difference in these two files, and since pydub is using ffmpeg, what do I need to change to make it do exactly the same as the ffmpeg command ?

  


  Not working

  


  from pydub import AudioSegment
>>> audio = AudioSegment.from_wav("input.wav")
>>> slice = audio[1000:3000]
>>> slice.export("pydub_export.m4a", format="mp4", parameters=["-ac", "1", "-c:a", "libfdk_aac", "-profile:a", "aac_he", "-vbr", "2"])


  


  mediainfo output :

  


  General
Complete name                            : pydub_export.m4a
Format                                   : MPEG-4
Format profile                           : Base Media
Codec ID                                 : isom (isom/iso2/mp41)
File size                                : 11.7 KiB
Duration                                 : 2 s 115 ms
Overall bit rate mode                    : Constant
Overall bit rate                         : 45.1 kb/s
Writing application                      : Lavf58.29.100

Audio
ID                                       : 1
Format                                   : AAC LC SBR
Format/Info                              : Advanced Audio Codec Low Complexity with Spectral Band Replication
Commercial name                          : HE-AAC
Format settings                          : NBC
Codec ID                                 : mp4a-40-5
Duration                                 : 2 s 115 ms
Duration_LastFrame                       : -22 ms
Bit rate mode                            : Constant
Bit rate                                 : 41.4 kb/s
Channel(s)                               : 1 channel
Channel layout                           : C
Sampling rate                            : 44.1 kHz
Frame rate                               : 21.533 FPS (2048 SPF)
Compression mode                         : Lossy
Stream size                              : 10.7 KiB (92%)
Default                                  : Yes
Alternate group                          : 1


  


  Working

  


  $ffmpeg -i input.wav -acodec copy -ss 1 -to 3 input_slice.wav
$ffmpeg -i input_slice.wav -ac 1 -c:a libfdk_aac -profile:a aac_he -vbr 2 ffmpeg_export.m4a


  


  mediainfo output :

  


  General
Complete name                            : ffmpeg_export.m4a
Format                                   : MPEG-4
Format profile                           : Apple audio with iTunes info
Codec ID                                 : M4A  (isom/iso2)
File size                                : 11.2 KiB
Duration                                 : 2 s 112 ms
Overall bit rate mode                    : Constant
Overall bit rate                         : 43.6 kb/s
Writing application                      : Lavf58.29.100

Audio
ID                                       : 1
Format                                   : AAC LC SBR
Format/Info                              : Advanced Audio Codec Low Complexity with Spectral Band Replication
Commercial name                          : HE-AAC
Format settings                          : NBC
Codec ID                                 : mp4a-40-5
Duration                                 : 2 s 112 ms
Duration_LastFrame                       : -25 ms
Bit rate mode                            : Constant
Bit rate                                 : 39.9 kb/s
Channel(s)                               : 1 channel
Channel layout                           : C
Sampling rate                            : 44.1 kHz
Frame rate                               : 21.533 FPS (2048 SPF)
Compression mode                         : Lossy
Stream size                              : 10.3 KiB (91%)
Default                                  : Yes
Alternate group                          : 1


  


  I already tried moving metadata to the front with -movflags faststart on the broken file and it didn't make a difference.

  


• Using FFMPEG with Xvfb, Can't get a smooth video output

  13 juillet 2020, par Emax

  I'm trying to stream to twitch from a linux server, I've installed Xvfb and FFMPEG, the live starts fine, but I can't get a smooth video output.

  


  Setps :

  


  Xvfb :1 -screen 0 1920x1080x24 &amp;&#xA;export DISPLAY=:1&#xA;&#xA;&#xA;ffmpeg -probesize 60M -video_size "1920x1080" -framerate 60 -f x11grab -i :1.0 -f flv -ac 2 -crf 23 \&#xA;       -vcodec libx264 -g 120 -b:v 3000k -minrate 3000k -maxrate 3000k -pix_fmt yuv420p\&#xA;       -s "1920x1080" -preset veryfast -tune zerolatency -acodec libmp3lame -threads 4 -strict normal \&#xA;       -bufsize 12000k "rtmp://live-mil.twitch.tv/app/<key>"&#xA;</key>

  


  I'm 100% sure that the app I'm trying to record output 60fps

  


  Also the FFMPEG output is

  


  ffmpeg version 4.1.6-1~deb10u1 Copyright (c) 2000-2020 the FFmpeg developers&#xA;  built with gcc 8 (Debian 8.3.0-6)&#xA;  configuration: --prefix=/usr --extra-version=&#x27;1~deb10u1&#x27; --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --arch=amd64 --enable-gpl --disable-stripping --enable-avresample --disable-filter=resample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libcodec2 --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libjack --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librsvg --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-lv2 --enable-omx --enable-openal --enable-opengl --enable-sdl2 --enable-libdc1394 --enable-libdrm --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libx264 --enable-shared&#xA;  libavutil      56. 22.100 / 56. 22.100&#xA;  libavcodec     58. 35.100 / 58. 35.100&#xA;  libavformat    58. 20.100 / 58. 20.100&#xA;  libavdevice    58.  5.100 / 58.  5.100&#xA;  libavfilter     7. 40.101 /  7. 40.101&#xA;  libavresample   4.  0.  0 /  4.  0.  0&#xA;  libswscale      5.  3.100 /  5.  3.100&#xA;  libswresample   3.  3.100 /  3.  3.100&#xA;  libpostproc    55.  3.100 / 55.  3.100&#xA;Input #0, x11grab, from &#x27;:1.0&#x27;:&#xA;  Duration: N/A, start: 1594669358.267783, bitrate: N/A&#xA;    Stream #0:0: Video: rawvideo (BGR[0] / 0x524742), bgr0, 1920x1080, 60 fps, 59.94 tbr, 1000k tbn, 1000k tbc&#xA;Stream mapping:&#xA;  Stream #0:0 -> #0:0 (rawvideo (native) -> h264 (libx264))&#xA;Press [q] to stop, [?] for help&#xA;[libx264 @ 0x55a2b7e28ec0] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX FMA3 BMI2 AVX2&#xA;[libx264 @ 0x55a2b7e28ec0] profile High, level 4.2&#xA;[libx264 @ 0x55a2b7e28ec0] 264 - core 155 r2917 0a84d98 - H.264/MPEG-4 AVC codec - Copyleft 2003-2018 - http://www.videolan.org/x264.html - options: cabac=1 ref=1 deblock=1:0:0 analyse=0x3:0x113 me=hex subme=2 psy=1 psy_rd=1.00:0.00 mixed_ref=0 me_range=16 chroma_me=1 trellis=0 8x8dct=1 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=0 threads=4 lookahead_threads=4 sliced_threads=1 slices=4 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=0 weightp=1 keyint=120 keyint_min=12 scenecut=40 intra_refresh=0 rc_lookahead=0 rc=crf mbtree=0 crf=23.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 vbv_maxrate=3000 vbv_bufsize=12000 crf_max=0.0 nal_hrd=none filler=0 ip_ratio=1.40 aq=1:1.00&#xA;Output #0, flv, to &#x27;rtmp://live.twitch.tv/app/<key>&#x27;:&#xA;  Metadata:&#xA;    encoder         : Lavf58.20.100&#xA;    Stream #0:0: Video: h264 (libx264) ([7][0][0][0] / 0x0007), yuv420p, 1920x1080, q=-1--1, 3000 kb/s, 60 fps, 1k tbn, 60 tbc&#xA;    Metadata:&#xA;      encoder         : Lavc58.35.100 libx264&#xA;    Side data:&#xA;      cpb: bitrate max/min/avg: 3000000/0/3000000 buffer size: 12000000 vbv_delay: -1&#xA;frame=  436 fps= 61 q=22.0 size=     287kB time=00:00:08.73 bitrate= 269.1kbits/s dup=0 drop=0 speed=1.22x&#xA;</key>

  


  I've also tryed to output the recording to an mp4 video file but I got the same result : a laggy video, It's like ffmpeg is recording the input at a lower framerate than 60, how can I fix this ?

  


• FFMPEG sync video from image2pipe with audio from RTMP

  4 juin 2021, par AndreaC

  I have an rtmp url, and i need to put overlay using opencv and keeping audio.

  


  It works well, exept for syncronization between audio and video.

  


  with this command

  


  ffmpeg -re -y -f image2pipe -i - -i rtmp://192.168.178.32:1935/opencv-hls/test -map 0:v:0 -vcodec libx264 -g 50 -keyint_min 50 -map 1:a:0 -b:a 128k -f mpegts -codec:v mpeg1video -b:v 700k -s 1024x576 -bf 0 -q 1 http://localhost:3000/mystream


  


  I open an image2pipe where i send my frame with overlay, and i use the same input of opencv as second command for ffmpeg to acquire audio and send all to mpegts url

  


  This is the ffmpeg output

  


  ffmpeg version 4.1.4-1build2 Copyright (c) 2000-2019 the FFmpeg developers
  built with gcc 9 (Ubuntu 9.2.1-4ubuntu1)
  configuration: --prefix=/usr --extra-version=1build2 --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --arch=amd64 --enable-gpl --disable-stripping --enable-avresample --disable-filter=resample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libcodec2 --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libjack --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librsvg --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzmq --enable-libzvbi --enable-lv2 --enable-omx --enable-openal --enable-opengl --enable-sdl2 --enable-libdc1394 --enable-libdrm --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libx264 --enable-shared
  libavutil      56. 22.100 / 56. 22.100
  libavcodec     58. 35.100 / 58. 35.100
  libavformat    58. 20.100 / 58. 20.100
  libavdevice    58.  5.100 / 58.  5.100
  libavfilter     7. 40.101 /  7. 40.101
  libavresample   4.  0.  0 /  4.  0.  0
  libswscale      5.  3.100 /  5.  3.100
  libswresample   3.  3.100 /  3.  3.100
  libpostproc    55.  3.100 / 55.  3.100
Input #0, image2pipe, from 'pipe:':
  Duration: N/A, bitrate: N/A
    Stream #0:0: Video: mjpeg, yuvj420p(pc, bt470bg/unknown/unknown), 1024x576 [SAR 1:1 DAR 16:9], 25 fps, 25 tbr, 25 tbn, 25 tbc
Input #1, flv, from 'rtmp://192.168.178.32:1935/opencv-hls/test':
  Metadata:
    Server          : NGINX RTMP (github.com/arut/nginx-rtmp-module)
    displayWidth    : 1024
    displayHeight   : 576
    fps             : 0
    profile         : 
    level           : 
  Duration: 00:00:00.00, start: 4.639000, bitrate: N/A
    Stream #1:0: Audio: aac (LC), 44100 Hz, stereo, fltp
    Stream #1:1: Video: h264 (Constrained Baseline), yuv420p(progressive), 1024x576, 29.58 fps, 29.58 tbr, 1k tbn
Stream mapping:
  Stream #0:0 -> #0:0 (mjpeg (native) -> mpeg1video (native))
  Stream #1:0 -> #0:1 (aac (native) -> mp2 (native))
[swscaler @ 0x55f256d63980] deprecated pixel format used, make sure you did set range correctly
Output #0, mpegts, to 'http://localhost:3000/mystream':
  Metadata:
    encoder         : Lavf58.20.100
    Stream #0:0: Video: mpeg1video, yuv420p(progressive), 1024x576 [SAR 1:1 DAR 16:9], q=2-31, 700 kb/s, 25 fps, 90k tbn, 25 tbc
    Metadata:
      encoder         : Lavc58.35.100 mpeg1video
    Side data:
      cpb: bitrate max/min/avg: 0/0/700000 buffer size: 0 vbv_delay: -1
    Stream #0:1: Audio: mp2, 44100 Hz, stereo, s16, 128 kb/s
    Metadata:
      encoder         : Lavc58.35.100 mp2


  


  I always have a delay between audio and video and it increese with time.
Do you have any idea on how to sync them ?

  


  thanks
Andrea