Recherche avancée

Sur d’autres sites (7024)

• How to set time_base when muxing AVI with libavformat ?

  18 mai 2012, par Anastasia

  In my application I receive from a remote server synchronized video
  (mpeg4) and audio (mp3) and mux them to avi file. The video comes
  frame-by-frame, and the audio comes in small chunks, say 200-250 ms.
  Both video frames and audio chunks have timestamps in milliseconds.

  My question is how to set audio time_base and pts correctly ?
  For video I set time_base.num = framerate, time_base.den = 1 ; and
  calculate pts as follows :

    AVRational time_base_1kHz; 
  
    time_base_1kHz.num = 1; 
  
    time_base_1kHz.den = 1000; 
  
    packet.pts = av_rescale_q(timeStamp - baseTimeStamp_, time_base_1kHz, videoStream_->time_base); 

  where baseTimeStamp_ is the 1st timestamp of the stream.

  But if I try do similar calculation for audio, I don't get playable
  avi. If I always set to audio AV_NOPTS_VALUE, then avi has playable
  video, but no audio.

  So what are the correct values for audio time_base and pts's ?
  Do I set time_base and pts's for video correctly ?

• Transcoding Mp4 video on Android with FFMPEG

  18 octobre 2012, par geeknizer

  I've compiled FFMPEG binary from Bambuser project (refer question) and have pushed binary and .so files to application directory.

  But when I try running FFMPEG with input file, it always complains file not found.

  1|root@android:/data/data/com.bambuser.broadcaster # ls                        
  
  cache           libavcodec.so   libavfilter.so  libswscale.so
  
  ffmpeg          libavcore.so    libavformat.so  tutorial.mp4
  
  lib             libavdevice.so  libavutil.so
  
  1|root@android:/data/data/com.bambuser.broadcaster # ./ffmpeg -i tutorial.mp4 out.mp4                                                              
  
  FFmpeg version UNKNOWN, Copyright (c) 2000-2010 the FFmpeg developers
  
    built on May  8 2012 10:11:37 with gcc 4.4.3
  
    configuration: --target-os=linux --cross-prefix=arm-linux-androideabi- --arch=arm --sysroot=/home/tarandeep/tools/android-ndk/platforms/android-3/arch-arm --soname-prefix=/data/data/com.bambuser.broadcaster/lib/ --enable-shared --disable-symver --enable-small --optimization-flags=-O2 --disable-everything --enable-encoder=mpeg2video --enable-encoder=nellymoser --prefix=../build/ffmpeg/armeabi-v7a --extra-cflags='-march=armv7-a -mfloat-abi=softfp' --extra-ldflags=
  
    libavutil     50.34. 0 / 50.34. 0
  
    libavcore      0.16. 0 /  0.16. 0
  
    libavcodec    52.99. 1 / 52.99. 1
  
    libavformat   52.88. 0 / 52.88. 0
  
    libavdevice   52. 2. 2 / 52. 2. 2
  
    libavfilter    1.69. 0 /  1.69. 0
  
    libswscale     0.12. 0 /  0.12. 0
  
  tutorial.mp4: No such file or directory

  I've tried placing file in /sdcard and other locations, I always get same output

• Encoding for HTTP Live Streaming with Xuggle

  26 mai 2012, par Luuk D. Jansen

  I have created a server system based on Xuggle to encode an incoming file to H264 and segment it. However, when playing the video back in Quicktime it almost works (with a small hiccup in the audio sometimes) but when changing fro one quality stream to another the image gets lost.

  So I ran the 'mediastreamvalidator'and got the following error :

  ERROR : (-1) Unknown video codec : 1836069494 (program 0, track 0)
  ERROR : (-1) failed to parse segment as either an MPEG-2 TS or an ES

  So I used FFMPEG to get some info on the codex :
  The result of my Xuggler encoding :

  Input #0, mpegts, from 'segment_0.ts':
  
    Duration: 00:00:09.40, start: 0.000000, bitrate: 3618 kb/s
  
    Program 1 
  
      Metadata:
  
        service_name    : Service01
  
        service_provider: FFmpeg
  
      Stream #0.0[0x100]: Video: mpeg2video (Main), yuv420p, 960x540 [PAR 1:1 DAR 16:9], 104857 kb/s, 25 fps, 25 tbr, 90k tbn, 50 tbc
  
      Stream #0.1[0x101]: Audio: mp2, 48000 Hz, stereo, s16, 128 kb/s

  The result of a file created by Compressor :

  Seems stream 0 codec frame rate differs from container frame rate: 180000.00 (180000/1) -> 25.00 (25/1)
  
  Input #0, mpegts, from 'fileSequence1.ts':
  
    Duration: 00:00:09.97, start: 19.984578, bitrate: 5308 kb/s
  
    Program 1 
  
      Stream #0.0[0x101]: Video: h264 (Main), yuv420p, 960x540, 25 tbr, 90k tbn, 180k tbc
  
      Stream #0.1[0x102]: Audio: aac, 22050 Hz, stereo, s16, 32 kb/s

  The main difference seems to me that for the Xuggler encoded file it says Video : mpeg2video instead of h264. However, while encoding I did specifically set the Coder to ICodec.ID.CODEC_ID_H264.

  How can I force it to use h264. The same with audio. I specified AAC and get MP2.

  I subsequent used FFMPEG directly and that results in :

  Input #0, mpegts, from 'encoded.ts':
  
    Duration: 00:00:24.16, start: 1.400000, bitrate: 360 kb/s
  
    Program 1 
  
      Metadata:
  
        service_name    : Service01
  
        service_provider: FFmpeg
  
      Stream #0.0[0x100]: Video: h264 (Main), yuv420p, 1920x1080 [PAR 1:1 DAR 16:9], 25 fps, 25 tbr, 90k tbn, 50 tbc
  
      Stream #0.1[0x101](eng): Audio: aac, 48000 Hz, stereo, s16, 57 kb/s

  That looks better. I could use FFMPEG directly, but by using Xuggler I can segment the file while easier keep track of progress of the process.