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• How to make a MPEG-DASH MPD which starts the playback in the middle of the first segment ?

  18 septembre 2018, par ravin.wang

  Here are the reproduce steps :

  1. Normalize an H.264 video stream

     ffmpeg -i 2.h264 -c:v libx264 -intra -r 25 -vf scale=640x360,setdar=16:9 2@25fps@intra@640x360.h264

     (*) After that, I got an H.264 stream where all pictures are H.264 IDR frames, and fps is 25, resolution is 640x360, aspect-ratio is 16:9.

  2. Generate an MP4 file

     MP4Box -add 2@25fps@intra@640x360.h264:timescale=1000 -fps 25 2@25fps@intra@640x360.mp4

  3. Make dash MP4 fragmented content, including init mp4, .m4s files and one .mpd file

     MP4Box -dash 5000 -frag 5000 -dash-scale 1000 -frag-rap -segment-name ’seg_second$Number$’ -segment-timeline -profile live 2@25fps@intra@640x360.mp4

  4. Copy and publish all these files to a folder under one HTTPD server

  5. I want to play from 4s of the first segment, and don’t display any frames before 4s, so I changed the .MPD file to modify the fields "SegmentTemplate@presentationTimeOffset", "SegmentTimeline:S@d/t", like as :
     

     <?xml version="1.0"?>
<mpd xmlns="urn:mpeg:dash:schema:mpd:2011" minbuffertime="PT1.500S" type="static" mediapresentationduration="PT0H0M26.000S" maxsegmentduration="PT0H0M5.000S" profiles="urn:mpeg:dash:profile:isoff-live:2011">
<period duration="PT0H0M26.000S">
<adaptationset segmentalignment="true" maxwidth="640" maxheight="360" maxframerate="25" par="16:9" lang="und">
 <segmenttemplate presentationtimeoffset="4000" media="seg_second$Number$.m4s" timescale="1000" startnumber="1" initialization="seg_secondinit.mp4">
   <segmenttimeline>
       <s d="1000" t="4000"></s>
       <s d="5000" r="4"></s>
   </segmenttimeline>
  </segmenttemplate>
<representation mimetype="video/mp4" codecs="avc3.64101E" width="640" height="360" framerate="25" sar="1:1" startwithsap="1" bandwidth="2261831">
</representation>
</adaptationset>
</period>
</mpd>

     
     

  6. Play the MPD url from VLC player, or Edge browser, it always starts the the first frame of the first segment, the frames between 0s 4s are also displayed unexpectedly.

  What’s wrong with my steps ? Or any other options for it ?

• MPD MPEG-DASH - Shows only one bitrate

  13 août 2018, par Justin Rec

  Help. I wont show bitrate.
  player.getBitrateInfoListFor("video") ;
  Shows only one bitrate - 454948

  manifest.mpd generated by GPAC

   <period duration="PT0H21M48.338S">
  
    <adaptationset segmentalignment="true" group="1" maxwidth="270" maxheight="480" maxframerate="2070000/93437" par="270:480" lang="und">
  
     <representation mimetype="video/mp4" codecs="avc3.640015" width="270" height="480" framerate="2070000/93437" sar="1:1" startwithsap="1" bandwidth="454948">
  
      <segmenttemplate media="480_bbb/segment__track1_$Number$.m4s" timescale="2070000" startnumber="1" duration="8280000" initialization="480_bbb/segment__track1_init.mp4"></segmenttemplate>
  
     </representation>
  
    </adaptationset>
  
    <adaptationset segmentalignment="true" group="1" maxwidth="202" maxheight="360" maxframerate="2070000/93437" par="202:360" lang="und">
  
     <representation mimetype="video/mp4" codecs="avc3.64000D" width="202" height="360" framerate="2070000/93437" sar="1:1" startwithsap="1" bandwidth="281508">
  
      <segmenttemplate media="360_bbb/segment__track1_$Number$.m4s" timescale="2070000" startnumber="1" duration="8280000" initialization="360_bbb/segment__track1_init.mp4"></segmenttemplate>
  
     </representation>
  
    </adaptationset>
  
    <adaptationset segmentalignment="true" group="1" maxwidth="134" maxheight="240" maxframerate="2070000/93437" par="134:240" lang="und">
  
     <representation mimetype="video/mp4" codecs="avc3.64000B" width="134" height="240" framerate="2070000/93437" sar="1:1" startwithsap="1" bandwidth="182832">
  
      <segmenttemplate media="240_bbb/segment__track1_$Number$.m4s" timescale="2070000" startnumber="1" duration="8280000" initialization="240_bbb/segment__track1_init.mp4"></segmenttemplate>
  
     </representation>
  
    </adaptationset>
  
    <adaptationset segmentalignment="true" group="1" maxwidth="80" maxheight="144" maxframerate="2070000/93437" par="80:144" lang="und">
  
     <representation mimetype="video/mp4" codecs="avc3.640009" width="80" height="144" framerate="2070000/93437" sar="1:1" startwithsap="1" bandwidth="99667">
  
      <segmenttemplate media="144_bbb/segment__track1_$Number$.m4s" timescale="2070000" startnumber="1" duration="8280000" initialization="144_bbb/segment__track1_init.mp4"></segmenttemplate>
  
     </representation>
  
    </adaptationset>
  
    <adaptationset segmentalignment="true" lang="und">
  
     <representation mimetype="audio/mp4" codecs="mp4a.40.2" startwithsap="1" bandwidth="66056">
  
      <audiochannelconfiguration schemeiduri="urn:mpeg:dash:23003:3:audio_channel_configuration:2011" value="1"></audiochannelconfiguration>
  
      <segmenttemplate media="audio_bbb/segment__track2_$Number$.m4s" timescale="48000" startnumber="1" duration="192000" initialization="audio_bbb/segment__track2_init.mp4"></segmenttemplate>
  
     </representation>
  
    </adaptationset>
  
   </period>

  player.getBitrateInfoListFor("video") ;
  Shows only one bitrate - 454948

• How to use Google's Cloud Speech-to-Text REST API to transcribe a video

  24 juillet 2018, par mrb

  I’d like to have the transcript of 2 people speaking in a video, but I get an empty response from the Cloud Speech-to-Text API

  Approach :

  I have a 56 minute video file containing a conversation between two people. I would like to have the transcript of that conversation, and I would like to use Google’s Cloud Speech-to-Text API to get that.

  To save a little on my Google Cloud Storage I converted to video to audio first by using mmpeg.

  First I’d tried to figure out the audio codec by using the command below, and it looks like AAC.
  ffmpeg -i video.mp4

  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'videoplayback.mp4':
  
    Metadata:
  
      major_brand     : mp42
  
      minor_version   : 0
  
      compatible_brands: isommp42
  
      creation_time   : 2015-12-30T08:17:14.000000Z
  
    Duration: 00:56:03.99, start: 0.000000, bitrate: 362 kb/s
  
      Stream #0:0(und): Video: h264 (Constrained Baseline) (avc1 / 0x31637661), yuv420p, 490x360 [SAR 1:1 DAR 49:36], 264 kb/s,     29.97 fps, 29.97 tbr, 30k tbn, 59.94 tbc (default)
  
      Metadata:
  
        handler_name    : VideoHandler
  
      Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 96 kb/s (default)
  
      Metadata:
  
        creation_time   : 2015-12-30T08:17:31.000000Z
  
        handler_name    : IsoMedia File Produced by Google, 5-11-2011    

  So I took that from the video by using :
  ffmpeg -i video.mp4 -vn -acodec copy myaudio.aac

  Details so far :
  ffmpeg -i myaudio.aac
  Outputs :

  Input #0, aac, from 'myaudio.aac':
  
    Duration: 00:56:47.49, bitrate: 97 kb/s
  
      Stream #0:0: Audio: aac (LC), 44100 Hz, stereo, fltp, 97 kb/s

  After that I converted it to opus because I’m told that opus is better
  ffmpeg -i myaudio.aac -acodec libopus -b:a 97k -vbr on -compression_level 10 myaudio.opus

  Info so far :
  opusinfo myaudio.opus
  

  User comments section follows...
  
      encoder=Lavc58.18.100 libopus
  
  Opus stream 1:
  
      Pre-skip: 312
  
      Playback gain: 0 dB
  
      Channels: 2
  
      Original sample rate: 48000Hz
  
      Packet duration:   20.0ms (max),   20.0ms (avg),   20.0ms (min)
  
      Page duration:   1000.0ms (max), 1000.0ms (avg), 1000.0ms (min)
  
      Total data length: 29956714 bytes (overhead: 0.872%)
  
      Playback length: 56m:03.990s
  
      Average bitrate: 71.24 kb/s, w/o overhead: 70.62 kb/s

  I this point I uploaded the myaudio.opus to the Google Cloud Storage.

  curl POST 1
  I started the speech recognition by doing a POST with curl :

  curl --request POST  --header "Content-Type: application/json" --url 'https://speech.googleapis.com/v1/speech:longrunningrecognize?fields=done%2Cerror%2Cmetadata%2Cname%2Cresponse&key={MY_API_KEY}' --data '{"audio": {"uri": "gs://{MY_BUCKET}/myaudio.opus"},"config": {"encoding": "OGG_OPUS", "sampleRateHertz": 48000, "languageCode": "en-US"}}'

  Response : {"name": "123456789"}
  123456789 was not the actual value.

  curl GET 1
  Now I wanted to have the results :

  curl --request GET --url 'https://speech.googleapis.com/v1/operations/123456789?fields=done%2Cerror%2Cmetadata%2Cname%2Cresponse&key={MY_API_KEY}'

  This gave me the error : Error : Unable to recognize speech, possible error in encoding or channel config. Please correct the config and retry the request.

  So I updated the encoding configuration from OGG_OPUS to LINEAR16.

  curl POST 2
  Did the post again :

  curl --request POST  --header "Content-Type: application/json" --url 'https://speech.googleapis.com/v1/speech:longrunningrecognize?fields=done%2Cerror%2Cmetadata%2Cname%2Cresponse&key={MY_API_KEY}' --data '{"audio": {"uri": "gs://{MY_BUCKET}/myaudio.opus"},"config": {"encoding": "LINEAR16", "sampleRateHertz": 48000, "languageCode": "en-US"}}'

  Response : {"name": "987654321"}

  curl GET 2
  

  curl --request GET --url 'https://speech.googleapis.com/v1/operations/987654321?fields=done%2Cerror%2Cmetadata%2Cname%2Cresponse&key={MY_API_KEY}'

  Response :

  {
  
    "name": "987654321",
  
    "metadata": {
  
      "@type": "type.googleapis.com/google.cloud.speech.v1.LongRunningRecognizeMetadata",
  
      "progressPercent": 100,
  
      "startTime": "2018-06-08T11:01:24.596504Z",
  
      "lastUpdateTime": "2018-06-08T11:01:51.825882Z"
  
    },
  
    "done": true
  
  }

  The problem is that I don’t get the actual transcription. According the the documentation there should be a response key in the response containing the data.

  Since I’m kinda stuck here I’d like to know if I’m doing something completely wrong. I don’t have any technical or resource limitation so all suggestions are very welcome ! Also happy to change my approach.

  Thanks in advance ! Cheers