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• avformat/demux : preserve AV_PKT_FLAG_CORRUPT in parse_packet

  21 octobre 2021, par Alex Shumsky

  avformat/demux : preserve AV_PKT_FLAG_CORRUPT in parse_packet
  If original packet is corrupted, then parsed packet is probably corrupted too.
  
  Let the application decide what to do.
  Signed-off-by : Alex Shumsky <alexthreed@gmail.com>
  

  • [DH] libavformat/demux.c

• FFMpeg - add sound to video that already contain sound

  24 mars 2016, par jacky brown

  Here is what I have : input1.avi - video that contain sounds. input2.avi - video that doesn’t contain sounds. music.mp3 - audio file.

  I want to add background music(music.mp3 file) to the video.

  C :\input1.avi -i C :\music.mp3 -shortest -c:v copy -c:a copy C :\output1.avi
  then output1.avi is the same as input1 - movie with sounds but without the background music (music.mp3)

  when I try to use the other file (video without sounds) :

  C :\input2.avi -i C :\music.mp3 -shortest -c:v copy -c:a copy C :\output2.avi
  then output2.avi is the same as input2 + it have the background music.

  I tried to execute this too :

  C:\ffmpeg\bin>ffmpeg -i C:\input.avi -i C:\music.mp3 -shortest -c:v copy -filter_ complex "[1]volume=1.5[1a];[0][1a]amerge[a]" -map 0:v -map "[a]" -ac 2 C:\output1.avi

  but got the next error messsage :

  ffmpeg version N-78949-g6f5048f Copyright (c) 2000-2016 the FFmpeg developers
  
    built with gcc 5.3.0 (GCC)
  
    configuration: --enable-gpl --enable-version3 --disable-w32threads --enable-av
  
  isynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls --enab
  
  le-iconv --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --
  
  enable-libdcadec --enable-libfreetype --enable-libgme --enable-libgsm --enable-l
  
  ibilbc --enable-libmodplug --enable-libmfx --enable-libmp3lame --enable-libopenc
  
  ore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-libopus --ena
  
  ble-librtmp --enable-libschroedinger --enable-libsoxr --enable-libspeex --enable
  
  -libtheora --enable-libtwolame --enable-libvidstab --enable-libvo-amrwbenc --ena
  
  ble-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx
  
  264 --enable-libx265 --enable-libxavs --enable-libxvid --enable-libzimg --enable
  
  -lzma --enable-decklink --enable-zlib
  
    libavutil      55. 19.100 / 55. 19.100
  
    libavcodec     57. 27.101 / 57. 27.101
  
    libavformat    57. 28.100 / 57. 28.100
  
    libavdevice    57.  0.101 / 57.  0.101
  
    libavfilter     6. 39.100 /  6. 39.100
  
    libswscale      4.  0.100 /  4.  0.100
  
    libswresample   2.  0.101 /  2.  0.101
  
    libpostproc    54.  0.100 / 54.  0.100
  
  Input #0, avi, from 'C:\output1.avi':
  
    Metadata:
  
      encoder         : Lavf57.28.100
  
    Duration: 00:02:05.76, start: 0.000000, bitrate: 450 kb/s
  
      Stream #0:0: Video: mpeg4 (Simple Profile) (XVID / 0x44495658), yuv420p, 720
  
  x480 [SAR 1:1 DAR 3:2], 440 kb/s, 25 fps, 25 tbr, 25 tbn, 25 tbc
  
      Stream #0:1: Audio: mp3 (U[0][0][0] / 0x0055), 44100 Hz, stereo, s16p, 128 k
  
  b/s
  
  [mp3 @ 00000000005abc20] Skipping 0 bytes of junk at 32370.
  
  Input #1, mp3, from 'C:\music.mp3':
  
    Metadata:
  
      title           : Broadcast News Package - News Intro
  
      artist          : After Effects News Template
  
    Duration: 00:01:57.89, start: 0.025057, bitrate: 194 kb/s
  
      Stream #1:0: Audio: mp3, 44100 Hz, stereo, s16p, 192 kb/s
  
      Metadata:
  
        encoder         : Lavc56.26
  
  [Parsed_amerge_1 @ 0000000000610200] No channel layout for input 1
  
  [Parsed_amerge_1 @ 0000000000610200] No channel layout for input 2
  
  [AVFilterGraph @ 00000000005ddfe0] The following filters could not choose their
  
  formats: Parsed_amerge_1
  
  Consider inserting the (a)format filter near their input or output.
  
  Error configuring complex filters.
  
  I/O error

  So why input1 does not contain the background music ? and how can I decrease or increase the volume of music.mp3 file ?

• How would I assign multiple MMAP's from single file descriptor ?

  9 juin 2011, par Alex Stevens

  So, for my final year project, I'm using Video4Linux2 to pull YUV420 images from a camera, parse them through to x264 (which uses these images natively), and then send the encoded stream via Live555 to an RTP/RTCP compliant video player on a client over a wireless network. All of this I'm trying to do in real-time, so there'll be a control algorithm, but that's not the scope of this question. All of this - except Live555 - is being written in C. Currently, I'm near the end of encoding the video, but want to improve performance.

  To say the least, I've hit a snag... I'm trying to avoid User Space Pointers for V4L2 and use mmap(). I'm encoding video, but since it's YUV420, I've been malloc'ing new memory to hold the Y', U and V planes in three different variables for x264 to read upon. I would like to keep these variables as pointers to an mmap'ed piece of memory.

  However, the V4L2 device has one single file descriptor for the buffered stream, and I need to split the stream into three mmap'ed variables adhering to the YUV420 standard, like so...

  buffers[n_buffers].y_plane = mmap(NULL, (2 * width * height) / 3,
  
                                      PROT_READ | PROT_WRITE, MAP_SHARED,
  
                                      fd, buf.m.offset);
  
  buffers[n_buffers].u_plane = mmap(NULL, width * height / 6,
  
                                      PROT_READ | PROT_WRITE, MAP_SHARED,
  
                                      fd, buf.m.offset +
  
                                      ((2 * width * height) / 3 + 1) /
  
                                      sysconf(_SC_PAGE_SIZE));
  
  buffers[n_buffers].v_plane = mmap(NULL, width * height / 6,
  
                                      PROT_READ | PROT_WRITE, MAP_SHARED,
  
                                      fd, buf.m.offset +
  
                                      ((2 * width * height) / 3 + 
  
                                      width * height / 6 + 1) / 
  
                                      sysconf(_SC_PAGE_SIZE));

  Where "width" and "height" is the resolution of the video (eg. 640x480).

  From what I understand... MMAP seeks through a file, kind of like this (pseudoish-code) :

  fd = v4l2_open(...);
  
  lseek(fd, buf.m.offset + (2 * width * height) / 3);
  
  read(fd, buffers[n_buffers].u_plane, width * height / 6);

  My code is located in a Launchpad Repo here (for more background) :
  http://bazaar.launchpad.net/ alex-stevens/+junk/spyPanda/files (Revision 11)

  And the YUV420 format can be seen clearly from this Wiki illustration : http://en.wikipedia.org/wiki/File:Yuv420.svg (I essentially want to split up the Y, U, and V bytes into each mmap'ed memory)

  Anyone care to explain a way to mmap three variables to memory from the one file descriptor, or why I went wrong ? Or even hint at a better idea to parse the YUV420 buffer to x264 ? :P

  Cheers ! ^^