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• Free music recognition API

  12 mars 2014, par AmirH

  I'm developing an application to recognize the music played by speakers. It records 32 seconds of the sound played and send a request via an API of music recognition. So far I used Echonest. But my api_key has been banned because of to many requests since I published my freeware, used by more than 200 users.

  So I looked for MusicBrainz but it needs the exact duration of the entire song to receive a acceptable response, duration that my application can't guess.

  So I'm looking for a free music recognition API so my freeware works. Do you know one ?

  Note : I used Echonest by :

  • capturing 32 seconds with ffmpeg

  • sending this command via cURL :

    curl -F "api_key=XXX" -F "filetype=mp3" -F "track=@sound.mp3" "http://developer.echonest.com/api/v4/track/upload" > info.txt

  I tried to use MusicBrainz by :

  • capturing 32 seconds with ffmpeg

  • generating the fingerprint using Chromaprint with this command :

    fpcalc sound.mp3 > fingerprint.txt

  • sending this command via cURL :

    curl -F "client=XXX" -F "meta=recordings" -F "duration=32" -F "fingerprint=ABC" "http://api.acoustid.org/v2/lookup" > info.txt

• Can ffmpeg place Mp4 metainfo at the beginning of the file ?

  10 février 2014, par mczarnek

  As I understand, ffmpeg by default places all meta info at the end of the file when generating mp4s.
  Source : http://www.stoimen.com/blog/2010/11/12/how-to-make-mp4-progressive-with-qt-faststart/

  What I need to do is create the video, one frame at a time and then stream it. This is impossible if the header info is at the 'end' of the file. But is it possible to move this to the beginning or otherwise work around this ? I would definitely prefer to not have to switch to another library and use it instead.. we're already over-budget on this project.

  Edit : Has to be done within code as I am converting one frame at a time and would like to then instantly stream it instead of command like.

• HLS Playback Issues on Android with FFMPEG

  25 mai 2014, par Florian

  I am using the FFMPEG built of AppUnite with the latest patch for stagefright support in order to playback http live streams : https://review.appunite.com/#/c/1779/

  As the stream does not start at 0, I added the following code to avoid a black screen :

  struct Player {
  
     + int64_t video_start_time;
  
  }
  
  
  
  void player_get_video_duration(struct Player *player) {
  
  + player->video_start_time = 0;
  
  
  
  + for (i = 0; i < player->capture_streams_no; ++i) {
  
  +    AVStream *stream = player->input_streams[i];
  
  +       if (stream->start_time > 0) {
  
  +          player->video_start_time = av_rescale_q(
  
  +             stream->start_time, stream->time_base, AV_TIME_BASE_Q);
  
  +
  
  +          LOGI(3, "player_set_data_source stream[%d] start_time: %ld",
  
  +             i, player->video_start_time);
  
  +
  
  +           break;
  
  +       }
  
  +   }
  
  }
  
  
  
  enum WaitFuncRet player_wait_for_frame(
  
     struct Player *player, double time, int stream_no) {
  
  - int64_t current_time = av_gettime();
  
  + int64_t current_time = av_gettime() + player->video_start_time; 
  
  }

  However, as soon as the sleep_time in player_wait_for_frame drops below 0, playback freezes and then hangs waiting for a frame that never arrives. The queues allocated by player_alloc_queues function seem being not big enough to hold the real-time stream pushed in between player_open_input and player_start_decoding_threads. Increasing the number of nodes in the queue does not resolve the issue however. The issue seems to be clearly in the player_wait_for_frame method but I am unable to find a solution.

  I spent quite a lot time trying to resolve this nasty issue, but without success so far. Any help really appreciated !!!