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• iOS switching between audio & subtitle tracks added using ffmpeg

  27 décembre 2019, par Tony M

  Edit : Title altered to reflect that the answer and comments by @llogan cover switching between both audio and subtitle tracks.

  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, and I can switch between audio streams using the VLC player. 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 on iOS ?

  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)

• Right choice to play audio and video content

  22 juin 2012, par deimus

  What I'm doing :

  I need to play audio and video files that are not supported by Apple on iPhone/iPad for example mkv/mka files which my contain several audio channels.

  I'm using libffmpeg to find audio and video streams in media file.
  Video is being decoded with avcodec_decode_video2 and audio with avcodec_decode_audio3
  the return values are following for each function are following

  • avcodec_decode_video2 - returns AVFrame structure which encapsulates information about the video video frame from the pakcage, specifically is has data field which is a pointer to the picture/channel planes.
  • avcodec_decode_audio3 - returns samples of type int16_t * which I guess is the raw audio data

  So basically I've done all this and successfully decoding the media content.

  What I have to do :
  I've to play the audio and video accordingly using Apples services. The playback I need to perform should support mixing of audio channels while playing video, i.e. let say mkv file contains two audio channel and a video channel. So I would like to know which service will be the appropriate choice for me ? My research showed that AudioQueue service might be useful audio playback, and probably AVFoundation for video.

  Please help to find the right technology for my case i.e. video playeback + audio playback with possible audio channel mixing.

• Create and update HLS playlist programmatically

  26 février 2018, par Pierre P.

  I have a C++ application that records audio from my default input device, encodes it in AAC format and writes to a .aac file. I want to use HTTP Live Streaming to live stream this AAC file. According to this question, I have to create a FFMPEG script to split my audio file into several .ts files.

  # bitrate, width, and height, you may want to change this
  
  BR=512k
  
  WIDTH=432
  
  HEIGHT=240
  
  input=${1}
  
  
  
  # strip off the file extension
  
  output=$(echo ${input} | sed 's/\..*//' )
  
  
  
  # works for most videos
  
  ffmpeg -y -i ${input} -f mpegts -acodec libmp3lame -ar 48000 -ab 64k -s ${WIDTH}x${HEIGHT} -vcodec libx264 -b ${BR} -flags +loop -cmp +chroma -partitions +parti4x4+partp8x8+partb8x8 -subq 7 -trellis 0 -refs 0 -coder 0 -me_range 16 -keyint_min 25 -sc_threshold 40 -i_qfactor 0.71 -bt 200k -maxrate ${BR} -bufsize ${BR} -rc_eq 'blurCplx^(1-qComp)' -qcomp 0.6 -qmin 30 -qmax 51 -qdiff 4 -level 30 -aspect ${WIDTH}:${HEIGHT} -g 30 -async 2 ${output}-iphone.ts

  (It is slightly different in my case because I only work with audio)

  Can I do so programmatically in C++ and if so, do I have to use a third-part library or does macOS provide native functions to do so ?