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• ffmpeg audio and the iphone

  17 juin 2019, par michelle

  has anyone been able to make ffmpeg work with audio queues, I get an error when I try to create the queue.

  ret = avcodec_open(enc, codec);
  
  
  
  if (ret < 0) {
  
      NSLog(@"Error: Could not open video decoder: %d", ret); 
  
      av_close_input_file(avfContext); 
  
      return; 
  
  }
  
  
  
  
  
  if (audio_index >= 0) { 
  
      AudioStreamBasicDescription
  
      audioFormat;
  
  
  
      audioFormat.mFormatID = -1;
  
  
  
      audioFormat.mSampleRate =
  
      avfContext->streams[audio_index]->codec->sample_rate;
  
  
  
      audioFormat.mFormatFlags = 0;
  
  
  
      switch (avfContext->streams[audio_index]->codec->codec_id)
  
      {
  
      case CODEC_ID_MP3: 
  
          audioFormat.mFormatID = kAudioFormatMPEGLayer3; 
  
          break;
  
  
  
      case CODEC_ID_AAC: 
  
          audioFormat.mFormatID = kAudioFormatMPEG4AAC;
  
          audioFormat.mFormatFlags = kMPEG4Object_AAC_Main;
  
          break;
  
  
  
      case CODEC_ID_AC3:
  
          audioFormat.mFormatID = kAudioFormatAC3; 
  
          break; 
  
      default: 
  
          break; 
  
      }
  
  
  
      if (audioFormat.mFormatID != -1) { 
  
          audioFormat.mBytesPerPacket = 0; 
  
          audioFormat.mFramesPerPacket =
  
          avfContext->streams[audio_index]->codec->frame_size;
  
  
  
          audioFormat.mBytesPerFrame = 0;
  
  
  
          audioFormat.mChannelsPerFrame = avfContext->streams[audio_index]->codec->channels;
  
  
  
          audioFormat.mBitsPerChannel = 0;
  
  
  
          if (ret = AudioQueueNewOutput(&audioFormat, audioQueueOutputCallback, self, NULL, NULL, 0, &audioQueue)) {
  
  
  
              NSLog(@"Error creating audio output queue: %d", ret);
  
          }

  The issues only with the audio,

  Video is perfect if only I can figure out how to get audio queues to work.

  http://web.me.com/cannonwc/Site/Photos_6.html

  I though of remoteio but there is’nt much doc on that.

  I will share the code for the complete class with anyone that helps me get it to work.

  The idea is to have a single view controller that plays any streaming video passed to it, similar to ffplay on the iphone but without the sdl overhead.

• iPhone slow motion video transcode

  28 septembre 2019, par coverboy

  I’m developing upload video (taken from iPhone) to my server.

  However, I have no idea how to implement.

  Any source code objective-c or swift will be welcomed.

  I have 120fps or 240fps video (It’s a slo-mo).
  When I playback these video on my iPhone6. I can see slo-mo effect.
  (I know playback frame rate is 30fps.)

  I want to convert that video before upload to my server, from 120/240 fps to 30fps video. (I mean not adjusting playback frame rate, it means video transcode to 30fps.)
  Additionally, I want to check slo-mo effect start-point and end-point.
  (Maybe iPhone record this information to video binary(it might be reside in file’s header.)

  Well, I guess if I use ffmpeg library, it should be easy(?).

  So any suggestions will be welcomed.

• How to switch between audio streams added using ffmpeg on an iPhone ?

  24 décembre 2019, par Tony M

  I have an m.mp4 with English audio and want to add a second audio stream in Italian so that I can play either language using the iPhone. When I used this command :

  ffmpeg -i m.mp4 -i ita.mp3 -c copy -map 0 -map 1 out.mp4 

  The output from ffmpeg -i out.mp4 (see below) shows that a new audio stream is added, yet when I transfer the video to the TV app and play it on either MacOS or iOS it only plays the original English and I see no options to play other languages.

  How do I get it to be able to switch between either audio ?

  Here is the output from ffmpeg -i out.mp4:

      Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 400x300 [SAR 1:1 DAR 4:3], q=2-31, 482 kb/s, 23.98 fps, 23.98 tbr, 24k tbn, 24k tbc (default)
  
      Metadata:
  
        handler_name    : VideoHandler
  
      Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 102 kb/s (default)
  
      Metadata:
  
        handler_name    : SoundHandler
  
      Stream #0:2: Audio: mp3 (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 152 kb/s
  
      Metadata:
  
        encoder         : LAME3.100
  
  Stream mapping:
  
    Stream #0:0 -> #0:0 (copy)
  
    Stream #0:1 -> #0:1 (copy)
  
    Stream #1:0 -> #0:2 (copy)