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• using FFmpeg, how to decode H264 packets

  28 mars 2017, par Jun

  I’m new to FFmpeg struggling to decode H264 packets which can be obtained as an array of uint8_t.

  After many of investigations, I think it should be able to just put the array into an AVPacket like the below

  AVPacket *avpkt = (AVPacket *)malloc(sizeof(AVPacket) * 1);
  
  av_init_packet(avpkt);  
  
  avpkt->data = ct;   // ct is the array
  
  avpkt->length =....

  and decode by avcodec_decode_video2(). A part of the code is like

  ...
  
  codec = avcodec_find_decoder(CODEC_ID_H264);
  
  gVideoCodecCtx = avcodec_alloc_context();
  
  gFrame = avcodec_alloc_frame();
  
  avcodec_decode_video2(gVideoCodecCtx, gFrame, &frameFinished, packet);
  
  ...

  I guess I set all required properties properly but this function is returning only -1 :(

  I just found the -1 is coming from

  ret = avctx->codec->decode(avctx, picture, got_picture_ptr, avpkt) ;

  in the avcodec_decode_video2() ;

  Actually, what I’m wondering is if I can decode H264 packets (without RTP header) by avcodec_decode_video2().

  Thanks for the help in advance.

  ---

  /////////// added

  OK, I’m still trying to find a solution. What I’m doing now is the below

  ** the H264 stream in this RTP stream is encoded by FU-A

  1. receive a RTP packet

  2. look if the second byte of the RTP header is > 0 which means it’s the first packet (and possibly will be followed)

  3. see if the next RTP packet has > 0 at its second byte also, then it means the previous frame was a complete NAL or if this is < 0, the packet should be appended to the previous packet.

  4. remove all RTP header of the packets so it has only like FU indicator | FU header | NAL

  5. try play it with avcodec_decode_video2()

  but it’s only returning -1..... am I supposed to remove FU indicator and header too ??

  any suggestion will be very appreciated

  thanks in advance.

• Feeding a series of images to ffmpeg as each image is created [closed]

  5 février 2013, par Mark Schneider

  I'm trying to use ffmpeg to build a 1280x720 slide-show from a sequence of pictures and videos, but I have concerns about potential disk I/O bottleneck.

  I expect a typical slide-show to have about 50 pictures and 2-3 videos (10-15 seconds each at 30 fps). I would like to show each picture for 3-4 seconds (possibly with a
  Ken Burns effect) with a smooth 2 second crossfade between each set of pictures (or for pictures adjacent to videos - between the picture and the first/last frame of the video).

  Given about 50 pictures, the crossfades alone would amount to about 3,000 images (50 transitions x 2 secs/transition x 30 fps). And I suppose if I implement a Ken Burns effect during each picture's 3-4 second showing, I'd have to provide ffmpeg with individual images for each of those frames. (I'm writing a script in Ruby that will pull a list of images from a database and in turn call ImageMagick to create the individual images for each frame. As I understand it, the RMagick library interfaces with ImageMagick such that the output images come back as in-memory objects without needing to write to disk. FWIW, I'm developing in Windows 8 and will deploy to Heroku.)

  All of the slideshow examples I've found online feed ffmpeg a set of images which have already been created. However, in an effort to avoid waiting on considerable disk I/O, I'd like to feed each image to ffmpeg as the image is created rather than create them all in advance.

  Is there a way to send each image file to ffmpeg on the fly as the file is created in memory ?

• Using librtmpdump in android

  29 mars 2012, par iSun

  anyone can help to me to use rtmpdump in android ?

  i copied librtmp.so To libs\armeabi but i dont know that how can use it to playing an rtmp live stream using rtmpdump ?

  i use this code to my activity :

  static {
  
  
  
      System.loadLibrary("rtmp");
  
  
  
  }

  thanks in advance