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• Detecting video volume

  27 décembre 2016, par Johnathan Kanarek

  I’m streaming few RTMP streams through nginx and I want to check every few seconds what stream has the highest volume.
  Specifically these streams are of talking heads and I assume that usually only one of them is speaking at a time, and I’m trying to find which one.
  Since nginx can output hls (Apple http live streaming) I decided to check every few seconds the last segment of each stream using ffmpeg.
  Example :

  ffmpeg -f mp3 -i /my/path/camera67/123.ts -af "volumedetect" -f null /dev/null

  For some reason the max_volume is always zero (max_volume : 0.0 dB) and mean_volume seems meaningless regarding the volume.

  1. Do you have any idea why it’s always zero ?
  2. Is there a helpful way to understand mean_volume ?
  3. Can you think of a different tool that may give me the volume (e.g. mediainfo or ffprobe) ?

  I also tried :

  ffmpeg -f lavfi -i amovie=/my/path/camera67/123.ts,volumedetect

  This time I got :

  [mpegts @ 0x130bf40] start time for stream 1 is not set in estimate_timings_from_pts
  [mpegts @ 0x130bf40] Could not find codec parameters for stream 1 (Audio : aac ([15][0][0][0] / 0x000F), 0 channels, fltp) : unspecified sample rate
  Consider increasing the value for the ’analyzeduration’ and ’probesize’ options
  [Parsed_amovie_0 @ 0x130bcc0] No audio stream with index ’-1’ found
  [lavfi @ 0x130abc0] Error initializing filter ’amovie’ with args ’/my/path/camera67/123.ts’
  amovie=/my/path/camera67/123.ts,volumedetect : Invalid argument

  Any idea ?

  Thanks,
  T.

• FFMPEG resizing ouputs 0B file

  26 octobre 2016, par Rahul Kumar

  I am trying to resize a .mp4 file to different resolutions.
  This is the command I’m using :

  /c E:\videos\manage\ffmpeg.exe -i "E:\media\SampleVideo1280x7201mb.mp4" -s 800x600 -ar 22050 "E:\media\encoded\med_SampleVideo1280x7201mb.mp4" 2>&1

  This works for most of the files but for some input files, the file that outputs is 0B in size and This is the message I get :

  ffmpeg version N-69422-gf5722ba Copyright (c) 2000-2015 the FFmpeg developers built on Jan 30 2015 22:13:10 with gcc 4.9.2 (GCC) configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-avisynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enable-iconv --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libfreetype --enable-libgme --enable-libgsm --enable-libilbc --enable-libmodplug --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-librtmp --enable-libschroedinger --enable-libsoxr --enable-libspeex --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvo-aacenc --enable-libvo-amrwbenc --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxavs --enable-libxvid --enable-lzma --enable-decklink --enable-zlib libavutil 54. 18.100 / 54. 18.100 libavcodec 56. 21.101 / 56. 21.101 libavformat 56. 19.100 / 56. 19.100 libavdevice 56. 4.100 / 56. 4.100 libavfilter 5. 9.102 / 5. 9.102 libswscale 3. 1.101 / 3. 1.101 libswresample 1. 1.100 / 1. 1.100 libpostproc 53. 3.100 / 53. 3.100 Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'E:\media\SampleVideo1280x7201mb.mp4': Metadata: major_brand : isom minor_version : 512 compatible_brands: isomiso2avc1mp41 creation_time : 1970-01-01 00:00:00 encoder : Lavf53.24.2 Duration: 00:00:05.31, start: 0.000000, bitrate: 1589 kb/s Stream #0:0(und): Video: h264 (Main) (avc1 / 0x31637661), yuv420p, 1280x720 [SAR 1:1 DAR 16:9], 1205 kb/s, 25 fps, 25 tbr, 12800 tbn, 50 tbc (default) Metadata: creation_time : 1970-01-01 00:00:00 handler_name : VideoHandler Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, 5.1, fltp, 384 kb/s (default) Metadata: creation_time : 1970-01-01 00:00:00 handler_name : SoundHandler [libx264 @ 00000000036e00a0] using SAR=4/3 [libx264 @ 00000000036e00a0] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX [libx264 @ 00000000036e00a0] profile High, level 3.1 [libx264 @ 00000000036e00a0] 264 - core 144 r2525 40bb568 - H.264/MPEG-4 AVC codec - Copyleft 2003-2014 - http://www.videolan.org/x264.html - options: cabac=1 ref=3 deblock=1:0:0 analyse=0x3:0x113 me=hex subme=7 psy=1 psy_rd=1.00:0.00 mixed_ref=1 me_range=16 chroma_me=1 trellis=1 8x8dct=1 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=-2 threads=36 lookahead_threads=4 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=1 weightb=1 open_gop=0 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=1.40 aq=1:1.00 [libvo_aacenc @ 0000000002cca5c0] Unable to set encoding parameters Output #0, mp4, to 'E:\media\encoded\med_SampleVideo1280x7201mb.mp4': Metadata: major_brand : isom minor_version : 512 compatible_brands: isomiso2avc1mp41 encoder : Lavf53.24.2 Stream #0:0(und): Video: h264 (libx264), yuv420p, 800x600 [SAR 4:3 DAR 16:9], q=-1--1, 25 fps, 25 tbn, 25 tbc (default) Metadata: creation_time : 1970-01-01 00:00:00 handler_name : VideoHandler encoder : Lavc56.21.101 libx264 Stream #0:1(und): Audio: aac, 0 channels, 128 kb/s (default) Metadata: creation_time : 1970-01-01 00:00:00 handler_name : SoundHandler encoder : Lavc56.21.101 libvo_aacenc Stream mapping: Stream #0:0 -> #0:0 (h264 (native) -> h264 (libx264)) Stream #0:1 -> #0:1 (aac (native) -> aac (libvo_aacenc)) Error while opening encoder for output stream #0:1 - maybe incorrect parameters such as bit_rate, rate, width or height

  What am I doing wrong ? How do I fix this ?

• unsynchronized graph when h264 stream pause

  24 septembre 2016, par jorp

  Steps to reproduce :

  1.Connect android device to linux PC via USB.
  

  2.Run command on pc :
  adb shell screenrecord --output-format=h264 - | ffplay -analyzeduration 1 -

  3.Screenrecord(an Android system tool) will start to capture Android screen, encode by MediaCodec, generate h264 stream, send stream data to ffplay via pipe.

  4.PC will pop up ffplay window, and start display Android screen graphs

  ---

  If adb command runs when Android screen graph keeps static (no pixel color changes), ffplay window won’t pop up, until I touch somewhere to make Android graph changes.

  Question 1 : how to make ffplay to immidiately display the first frame of video when Android screen keeps static and adb commmand runs ?

  I’m not talking about "latency", if Android graph keeps changing, the graphic latency is within 2 second. It’s fast enough.

  when Android graph is static, run command without ffplay :
  adb shell screenrecord --output-format=h264 -

  screenrecord will output H264 stream data immidiately then pause.(See picture below).
  stream data comes first

  Does the data contain all information of first frame graph ?
  If so, how to make ffplay to display it immidiately ?

  ---

  Question 2 : how to make ffplay to immidiately display the latest frame of video when Android screen suddenly become static ?

  When Android screen start casting and Android graph suddenly become static, H264 data stream transfer will pause, while PC graph is different with Android graph.

  For example, I make a popup menu on Android disappear, there has been a fadeoff animation, PC graph pauses and display a translucent popup menu.(See picture below)

  latest graph on pc

  The first and latest frames of stream doesn’t display in ffplay immidiately, they are "missing".
  when Android screen go on changing, the "missing" frames displays.
  So it seems like the latest frames are always in buffer.

  I’ve tried adding these params to ffplay :
  

  -noinfbuf
-fflags nobuffer
-max_delay 0
-sync ext
-preset ultrafast
-tune zerolatency

  
  They cannot solve the problems

  Modifing Android ROM or screenrecord source, making a pixel color changes every frame, may solve the problems(I guess), but it would enlarge data stream, it’s the last choise.
  Is there any solution by adding params of ffplay, or by modifing screenrecord or ffplay source code ?

  PS : mplayer also has the same problem :
  mplayer -demuxer h264es -