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• Converting AAC stream to DASH MP4 with high fragment length precision

  5 mars 2017, par vdudouyt

  For my HTML5 project I need to create a fragmented MP4 file with a single audio stream (no video), each fragment of which has a duration of exactly 0.1 second.

  Accordingly to ffmpeg docs, you can accomplish that by passing a value in microseconds with ’-frag_duration’ - which I found to be working and playable with HTML5 MediaSource API :

  $ ffmpeg -y -i input.aac -c:a libfdk_aac -b:a 64k -level:v 13 -r 25 -strict experimental -movflags empty_moov+default_base_moof -frag_duration 100000 output.mp4

  As we have a 210 second audio split up by 0.1s fragments, I expect that in output.mp4 we’d have 2100 fragments, hence 2100 moof atoms. But, upon inspecting it I’ve figured out that we only have 1811 moof atoms - which means that some (or maybe even all) fragments are bigger than expected :

  $ python ~/git/mp4viewer/src/showboxes.py output.mp4 |grep moof|wc -l
  
  1811

  Could anybody tell me what’s wrong, and how could I accomplish what I want ?

  Right now my assumption is that during an encoding I have AAC frame length which is not a multiple of 0.1s, hence ffmpeg has no chance to produce the fragments that are strictly equal to 0.1s but I’m not sure. If somebody can confirm that - and let me know a way to explicitly set AAC frame_size in FFMPEG (I couldn’t find anything like that in the docs), or completely disprove this - it would be also highly appreciated.

• Adding multiple audio tracks and subtitles to dash manifest (mpd) with ffmpeg

  21 novembre 2020, par knona

  I'm trying to create a website to stream some videos. For each video, I extract video, audio and subtitles in 3 different folders. It happens that a video has multiple audio tracks and multiple subtitles. I did a lot of research and I don't know how to add all of them in the manifest. Right now, I use this command :

  



  ffmpeg -f webm_dash_manifest \
-i video1.mp4 -f webm_dash_manifest \
-i video2.mp4 -f webm_dash_manifest \
-i audio1.webm -f webm_dash_manifest \
-i audio2.webm -f webm_dash_manifest \
-i subtitles.vtt \
-c copy -map 0 -map 1 -map 2 -map 3 \
-f webm_dash_manifest -adaptation_sets "id=0,streams=v id=1,streams=a" manifest.mpd


  



  My two videos have different resolutions and bitrates, and it works perfectly. But I don't get any subtitles and my two audio tracks are considered like one same audio track which has two different bitrates (just like videos). I think I should have many adaptation_sets, but I don't know how to create them.

  



  How can I create that manifest the right way ?

  


• Shaka Player returns 4001 error - Node.js local web server playing MPEG-DASH

  27 mai 2020, par salgarji

  I've used Chrome inspection tool to access 'Console' and analyze what is happening. Complete error information :

  



  D {severity: 2, category: 4, code: 4001, data: Array(1), handled: false}
category: 4
code: 4001
data: Array(1)
0: "http://localhost:8080/dash_segmentos/video.mpd"
length: 1
__proto__: Array(0)
handled: false
severity: 2
__proto__: Object


  



  My Server.js file :

  



  var http = require('http');
var fs = require('fs');

console.log(__dirname);

var path='dash_segmentos/video.mpd';
fs.access(path, fs.constants.R_OK | fs.constants.W_OK, (err) => {
    if (err) {
        console.log("%s doesn't exist", path);
    } else {
        console.log('can read/write %s', path);
    }
});

const PORT=8080; 

fs.readFile('./player.html', function (err, html) {

    if (err) throw err;    

    http.createServer(function(request, response) {  
        response.setHeader("Access-Control-Allow-Headers", "authorization, content-type");
        response.setHeader("Access-Control-Allow-Origin", "*");
        response.setHeader("Access-Control-Allow-Headers", "Origin, X-Requested-With, Content-Type, Accept");
        response.writeHeader(200, {"Content-Type": "text/html"}); 
        response.write(html);  
        response.end();
    }).listen(PORT);
});


  



  As you can see I've added CORS (I guess it's correct) and a console.log to see if it's in the proper location. Furthermore, I've verified that file is accessible with fs.access and it returns can read/write dash_segmentos/video.mpd For this reason, I'm sure I am in the correct path and referencing the right file.

  



  The HTML code (player.html) provided to Server.js :

  



  &#xA;&#xA; &#xA; <code class="echappe-js">&lt;script type=&quot;text/javascript&quot;&amp;#xA;src=&quot;https://cdnjs.cloudflare.com/ajax/libs/shaka-player/2.5.11/shaka-player.compiled.js&quot;&gt;&lt;/script&gt;&#xA; &#xA; &#xA; 
  &#xA; &#xA; 
  &#xA;&#xA; &lt;script&gt;&amp;#xA;function initApp() { &amp;#xA;shaka.polyfill.installAll(); &amp;#xA;if (shaka.Player.isBrowserSupported()) { &amp;#xA; initPlayer(); &amp;#xA; } else { &amp;#xA; console.error(&amp;#x27;Browser not supported!&amp;#x27;);&amp;#xA; }}&amp;#xA;&amp;#xA;function initPlayer() { &amp;#xA;var video = document.getElementById( &amp;#x27;video&amp;#x27; );&amp;#xA;var player = new shaka.Player( video );&amp;#xA; window.player = player; &amp;#xA;player.addEventListener(&amp;#x27;error&amp;#x27;, onErrorEvent); &amp;#xA;player.load(path).then(function (){&amp;#xA;    console.log(&amp;#x27;Video loaded correctly&amp;#x27;);&amp;#xA; }).catch(onError);&amp;#xA;&amp;#xA;function onErrorEvent(event) {&amp;#xA; onError(event.detail); &amp;#xA; }&amp;#xA;function onError(error) {&amp;#xA; console.error(&amp;#x27;Codigo de error: &amp;#x27;, error.code, &amp;#x27; en &amp;#x27;, error);&amp;#xA; }&amp;#xA;}&amp;#xA;&lt;/script&gt;&#xA;&#xA;&lt;script&gt;&amp;#xA;var path=&amp;#x27;dash_segmentos/video.mpd&amp;#x27;;&amp;#xA;//var path=&amp;#x27;https://dash.akamaized.net/dash264/TestCases/2c/qualcomm/1/MultiResMPEG2.mpd&amp;#x27;;&amp;#xA;//the URL above is working! but it won&amp;#x27;t read my local mpd&amp;#xA;&amp;#xA;document.addEventListener(&amp;#x27;DOMContentLoaded&amp;#x27;, initApp);&amp;#xA;&amp;#xA; &lt;/script&gt;&#xA; &#xA;&#xA;
  

  



  I've tried changing the URL to an online resource and the player is properly working.

  



  My fluent-ffmpeg command which generates the video is :

  



  var ffmpeg = require('fluent-ffmpeg');

var grabacion = new ffmpeg();

grabacion.addInput('0')
.inputOptions(['-y -nostdin', '-f avfoundation', '-video_size 1280x720', '-framerate 30'])
.outputOptions(['-vcodec libx264', '-keyint_min 0', '-g 100', '-map 0:v', '-b:v 1000k', '-f dash',
 '-use_template 1', '-use_timeline 0', '-init_seg_name video0-$RepresentationID$-$Number$.mp4',
 '-media_seg_name video0-$RepresentationID$-$Number$.mp4','-single_file 0', '-remove_at_exit 0', '-window_size 20', '-seg_duration 4'])
.output('/path/to/files/dash_segmentos/video.mpd')
.run();


  



  The mpd manifest file is :

  



  &lt;?xml version="1.0" encoding="utf-8"?>&#xA;<mpd xmlns="urn:mpeg:dash:schema:mpd:2011" profiles="urn:mpeg:dash:profile:isoff-live:2011" type="static" mediapresentationduration="PT26.7S" maxsegmentduration="PT4.0S" minbuffertime="PT13.2S">&#xA;    <programinformation>&#xA;    </programinformation>&#xA;    <servicedescription>&#xA;    </servicedescription>&#xA;    <period start="PT0.0S">&#xA;        <adaptationset contenttype="video" startwithsap="1" segmentalignment="true" bitstreamswitching="true" framerate="30000/1001" maxwidth="1280" maxheight="720" par="16:9">&#xA;            <representation mimetype="video/mp4" codecs="avc1.7a001f" bandwidth="1000000" width="1280" height="720" sar="1:1">&#xA;                <segmenttemplate timescale="1000000" duration="4000000" initialization="video0-$RepresentationID$-$Number$.mp4" media="video0-$RepresentationID$-$Number$.mp4" startnumber="1">&#xA;                </segmenttemplate>&#xA;            </representation>&#xA;        </adaptationset>&#xA;    </period>&#xA;</mpd>&#xA;

  



  Is something about ffmpeg ? Permissions ? Pixel format ? Encoding ? I've tried with other mpd file provided by my Raspberry Pi using video4linux (v4l) and it returns the same error !

  



  I know that's a lot of code, but maybe you find it quicker than me. I guess it's a Shaka Player thing with the XML, but I can't explain how ffmpeg is wrongly creating XML code.

  



  Thank you in advance !!