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  • Algorithm when recording SegmentTimeline of MPEG-DASH MPD in shaka packager

    25 mars 2021, par jgkim0518

    I packaged a media stream by mpeg-dash transcoded video at twice the speed and audio at normal speed.
Here is the command :

    


    ffmpeg -re -stream_loop -1 -i timing_logic.mp4 -c:v hevc_nvenc -filter:v "setpts=2*PTS" -c:a libfdk_aac -map 0:v -map 0:a -f mpegts udp://xxx.xxx.xxx.xxx:xxxx?pkt_size=1316


    


    The source information used here is as follows :

    


    Input #0, mpegts, from '/home/test/timing_logic/timing_logic.mp4':
Duration: 00:00:30.22, start: 1.400000, bitrate: 16171 kb/s
Program 1
Metadata:
service_name : Service01
service_provider: FFmpeg
Stream #0:0[0x100]: Video: hevc (Main 10) (HEVC / 0x43564548), yuv420p10le(tv, bt709), 3840x2160 [SAR 1:1 DAR 16:9], 50 fps, 50 tbr, 90k tbn, 50 tbc
Stream #0:1[0x101](eng): Audio: mp2 ([3][0][0][0] / 0x0003), 48000 Hz, stereo, fltp, 128 kb/s Stream mapping:
Stream #0:0 -> #0:0 (hevc (native) -> hevc (hevc_nvenc))
Stream #0:1 -> #0:1 (mp2 (native) -> aac (libfdk_aac))
Press [q] to stop, [?] for help
frame= 0 fps=0.0 q=0.0 size= 0kB time=-577014:32:22.77 bitrate= -0.0kbits/s speed=N/A
frame= 0 fps=0.0 q=0.0 size= 0kB time=-577014:32:22.77 bitrate= -0.0kbits/s speed=N/A
Output #0, mpegts, to 'udp://xxx.xxx.xxx.xxx:xxxx?pkt_size=1316':
Metadata:
encoder : Lavf58.45.100
Stream #0:0: Video: hevc (hevc_nvenc) (Main 10), p010le, 3840x2160 [SAR 1:1 DAR 16:9], q=-1--1, 2000 kb/s, 50 fps, 90k tbn, 50 tbc
Metadata:
encoder : Lavc58.91.100 hevc_nvenc
Side data:
cpb: bitrate max/min/avg: 0/0/2000000 buffer size: 4000000 vbv_delay: N/A
Stream #0:1(eng): Audio: aac (libfdk_aac), 48000 Hz, stereo, s16, 139 kb/s
Metadata:
encoder : Lavc58.91.100 libfdk_aac


    


    My shaka packager command is :

    


    packager \ 'in=udp://xxx.xxx.xxx.xxx:xxxx,stream=video,init_segment=/home/test/timing_logic/package/video/0/video.mp4,segment_template=/home/test/timing_logic/package/video/0/$Time$.m4s' \
'in=udp://xxx.xxx.xxx.xxx:xxxx,stream=audio,init_segment=/home/test/timing_logic/package/audio/0/audio.mp4,segment_template=/home/test/timing_logic/package/audio/0/$Time$.m4a' \
--segment_duration 5 --fragment_duration 5 --minimum_update_period 5 --min_buffer_time 5 \
--preserved_segments_outside_live_window 24 --time_shift_buffer_depth 40 \
--allow_codec_switching --allow_approximate_segment_timeline --log_file_generation_deletion \
--mpd_output $OUTPUT/$output_mpd.mpd &


    


    Looking at the mpd generated as a result of packaging, the duration of the audio is twice that of the video, and the number of segments is half.
The following is the content of mpd :

    


    &lt;?xml version="1.0" encoding="UTF-8"?>&#xA;&#xA;<mpd xmlns="urn:mpeg:dash:schema:mpd:2011" profiles="urn:mpeg:dash:profile:isoff-live:2011" minbuffertime="PT5S" type="dynamic" publishtime="2021-03-23T10:01:57Z" availabilitystarttime="2021-03-23T09:59:55Z" minimumupdateperiod="PT5S" timeshiftbufferdepth="PT40S">&#xA;<period start="PT0S">&#xA;<adaptationset contenttype="audio" segmentalignment="true">&#xA;<representation bandwidth="140020" codecs="mp4a.40.2" mimetype="audio/mp4" audiosamplingrate="48000">&#xA;<audiochannelconfiguration schemeiduri="urn:mpeg:dash:23003:3:audio_channel_configuration:2011" value="2"></audiochannelconfiguration>&#xA;<segmenttemplate timescale="90000" initialization="/home/test/timing_logic/package/audio/0/audio.mp4" media="/home/test/timing_logic/package/audio/0/$Time$.m4a" startnumber="16">&#xA;<segmenttimeline>&#xA;<s t="6751436" d="449280"></s>&#xA;<s t="7200716" d="451200"></s>&#xA;<s t="7651916" d="449280"></s>&#xA;<s t="8101196" d="374400"></s>&#xA;<s t="8551196" d="449280"></s>&#xA;<s t="9000476" d="451200"></s>&#xA;<s t="9451674" d="449280"></s>&#xA;<s t="9900956" d="449280"></s>&#xA;<s t="10350236" d="451200"></s>&#xA;<s t="10801434" d="374400"></s>&#xA;</segmenttimeline>&#xA;</segmenttemplate>&#xA;</representation>&#xA;</adaptationset>&#xA;<adaptationset contenttype="video" width="3840" height="2160" framerate="90000/3600" segmentalignment="true" par="16:9">&#xA;<representation bandwidth="1520392" codecs="hvc1.2.4.L153" mimetype="video/mp4" sar="1:1">&#xA;<segmenttemplate timescale="90000" initialization="/home/test/timing_logic/package/video/0/video.mp4" media="/home/test/timing_logic/package/video/0/$Time$.m4s" startnumber="19">&#xA;<segmenttimeline>&#xA;<s t="16954440" d="900000" r="4"></s>&#xA;</segmenttimeline>&#xA;</segmenttemplate>&#xA;</representation>&#xA;</adaptationset>&#xA;</period>&#xA;</mpd>&#xA;

    &#xA;

    When looking at the MPD, it seems that the shaka packager checks the PTS or DTS of the TS when creating a segment and recording the contents of the SegmentTimeline.&#xA;But I couldn't understand even by looking at the MPEG standard documentation and the DASH-IF documentation.

    &#xA;

    My question is whether the packager refers to PTS or DTS when creating a segment.&#xA;How are SegmentTimeline's S@t and S@d recorded ?&#xA;What algorithm is the SegmentTimeline recorded with ? Please help me. Thank you.

    &#xA;

  • APPLY Strong to Buffer rule. Quit Switching Bit rates MPEG DASH

    14 juillet 2015, par Vinay

    I am using mpeg dash for adaptive bit rate streaming of video from my server.

    I have used ffmpeg and MP4Box to generate 4 different quality video files from my source .mp4

    The .mpd file generated has the below code

    &lt;?xml version="1.0"?>
    

    
<mpd xmlns="urn:mpeg:dash:schema:mpd:2011" minbuffertime="PT1.500000S" type="static" mediapresentationduration="PT0H3M1.42S" profiles="urn:mpeg:dash:profile:isoff-on-demand:2011">
    
 <programinformation moreinformationurl="http://gpac.sourceforge.net">
    
  
    
 </programinformation>
    

    
 <period duration="PT0H3M1.42S">
    
  <adaptationset segmentalignment="true" maxwidth="1920" maxheight="1080" maxframerate="24" par="16:9" lang="und" subsegmentstartswithsap="1">
    
   <representation mimetype="video/mp4" codecs="avc1.64000d" width="320" height="240" framerate="24" sar="1:1" startwithsap="1" bandwidth="375715">
    
    <baseurl>400_dashinit.mp4</baseurl>
    
    <segmentbase indexrangeexact="true" indexrange="904-1403">
    
      <initialization range="0-903"></initialization>
    
    </segmentbase>
    
   </representation>
    
   <representation mimetype="video/mp4" codecs="avc1.640015" width="420" height="270" framerate="24" sar="1:1" startwithsap="1" bandwidth="644824">
    
    <baseurl>700_dashinit.mp4</baseurl>
    
    <segmentbase indexrangeexact="true" indexrange="905-1404">
    
      <initialization range="0-904"></initialization>
    
    </segmentbase>
    
   </representation>
    
   <representation mimetype="video/mp4" codecs="avc1.64001f" width="1024" height="576" framerate="24" sar="1:1" startwithsap="1" bandwidth="1349484">
    
    <baseurl>1500_dashinit.mp4</baseurl>
    
    <segmentbase indexrangeexact="true" indexrange="905-1404">
    
      <initialization range="0-904"></initialization>
    
    </segmentbase>
    
   </representation>
    
   <representation mimetype="video/mp4" codecs="avc1.64001f" width="1280" height="720" framerate="24" sar="1:1" startwithsap="1" bandwidth="2264379">
    
    <baseurl>2500_dashinit.mp4</baseurl>
    
    <segmentbase indexrangeexact="true" indexrange="905-1404">
    
      <initialization range="0-904"></initialization>
    
    </segmentbase>
    
   </representation>
    
   <representation mimetype="video/mp4" codecs="avc1.640028" width="1920" height="1080" framerate="24" sar="1:1" startwithsap="1" bandwidth="3633049">
    
    <baseurl>4000_dashinit.mp4</baseurl>
    
    <segmentbase indexrangeexact="true" indexrange="906-1405">
    
      <initialization range="0-905"></initialization>
    
    </segmentbase>
    
   </representation>
    
  </adaptationset>
    
 </period>
    
</mpd>

    I am using video.js along with dash.js to playback the mpeg dash content on client side. The issue is that the video doesn’t playback perfectly when i simulate network conditions from chrome dev tools.

    It works at times and it doesn’t at others. For ex the stream starts with bit rate of 400kbps and then detects enough bandwidth available so it switches to 2500kbps. Then when i bring down my bandwidth to 400kbps again then the video freezes at some point of time.

    At times the video freezes after few initial seconds of playback when it tries to switch the stream. I think there might be some command line parameter that i am missing while generating my video files via ffmpeg or generating .mpd file via MP4Box.

    below are the commands i use for ffmpeg and MP4Box

    ffmpeg -y -i inputfile -c:a libfdk_aac -ac 2 -ab 128k -c:v libx264 -r 24 – g 24 -b:v 1500k -maxrate 1500k -bufsize 1000k -vf "scale=-1:720" outputfile.mp4
    

    

    
MP4Box -dash [DURATION] -rap -frag-rap -profile [PROFILE] -out [path/to/outpout.file] [path/to/input1.file] [path/to/input2.file] [path/to/input3.file]

    Also while i am generating .mpd files via MP4Box i am getting below warning in console

    [DASH]: Files have non-proportional track layouts (320x240 vs 420x270) but sample size and aspect ratio match, assuming precision issue
    
[DASH]: Files have non-proportional track layouts (320x240 vs 1024x576) but sample size and aspect ratio match, assuming precision issue
    
[DASH]: Files have non-proportional track layouts (320x240 vs 1280x720) but sample size and aspect ratio match, assuming precision issue
    
[DASH]: Files have non-proportional track layouts (320x240 vs 1920x1080) but sample size and aspect ratio match, assuming precision issue

    Whenever the video stops playing the chrome console has these logs

    Number of times the buffer has run dry: 25
    
Apply STRONG to buffer rule.
    
Quit switching bit rates.

    I don’t have any clue as to why the buffers run dry and it stops switching the bit rates.

    Anything that is predominantly wrong in the process ?

  • Algorithm when recording SegmentTimeline

    24 mars 2021, par jgkim0518

    I packaged a media stream by mpeg-dash transcoded video at twice the speed and audio at normal speed.&#xA;Here is the command :

    &#xA;

    ffmpeg -re -stream_loop -1 -i timing_logic.mp4 -c:v hevc_nvenc -filter:v "setpts=2*PTS" -c:a libfdk_aac -map 0:v -map 0:a -f mpegts udp://xxx.xxx.xxx.xxx:xxxx?pkt_size=1316&#xA;

    &#xA;

    The source information used here is as follows :

    &#xA;

    Input #0, mpegts, from &#x27;/home/test/timing_logic/timing_logic.mp4&#x27;:&#xA;Duration: 00:00:30.22, start: 1.400000, bitrate: 16171 kb/s&#xA;Program 1&#xA;Metadata:&#xA;service_name : Service01&#xA;service_provider: FFmpeg&#xA;Stream #0:0[0x100]: Video: hevc (Main 10) (HEVC / 0x43564548), yuv420p10le(tv, bt709), 3840x2160 [SAR 1:1 DAR 16:9], 50 fps, 50 tbr, 90k tbn, 50 tbc&#xA;Stream #0:1[0x101](eng): Audio: mp2 ([3][0][0][0] / 0x0003), 48000 Hz, stereo, fltp, 128 kb/s Stream mapping:&#xA;Stream #0:0 -> #0:0 (hevc (native) -> hevc (hevc_nvenc))&#xA;Stream #0:1 -> #0:1 (mp2 (native) -> aac (libfdk_aac))&#xA;Press [q] to stop, [?] for help&#xA;frame= 0 fps=0.0 q=0.0 size= 0kB time=-577014:32:22.77 bitrate= -0.0kbits/s speed=N/A&#xA;frame= 0 fps=0.0 q=0.0 size= 0kB time=-577014:32:22.77 bitrate= -0.0kbits/s speed=N/A&#xA;Output #0, mpegts, to &#x27;udp://xxx.xxx.xxx.xxx:xxxx?pkt_size=1316&#x27;:&#xA;Metadata:&#xA;encoder : Lavf58.45.100&#xA;Stream #0:0: Video: hevc (hevc_nvenc) (Main 10), p010le, 3840x2160 [SAR 1:1 DAR 16:9], q=-1--1, 2000 kb/s, 50 fps, 90k tbn, 50 tbc&#xA;Metadata:&#xA;encoder : Lavc58.91.100 hevc_nvenc&#xA;Side data:&#xA;cpb: bitrate max/min/avg: 0/0/2000000 buffer size: 4000000 vbv_delay: N/A&#xA;Stream #0:1(eng): Audio: aac (libfdk_aac), 48000 Hz, stereo, s16, 139 kb/s&#xA;Metadata:&#xA;encoder : Lavc58.91.100 libfdk_aac&#xA;

    &#xA;

    My shaka packager command is :

    &#xA;

    packager \ &#x27;in=udp://xxx.xxx.xxx.xxx:xxxx,stream=video,init_segment=/home/test/timing_logic/package/video/0/video.mp4,segment_template=/home/test/timing_logic/package/video/0/$Time$.m4s&#x27; \&#xA;&#x27;in=udp://xxx.xxx.xxx.xxx:xxxx,stream=audio,init_segment=/home/test/timing_logic/package/audio/0/audio.mp4,segment_template=/home/test/timing_logic/package/audio/0/$Time$.m4a&#x27; \&#xA;--segment_duration 5 --fragment_duration 5 --minimum_update_period 5 --min_buffer_time 5 \&#xA;--preserved_segments_outside_live_window 24 --time_shift_buffer_depth 40 \&#xA;--allow_codec_switching --allow_approximate_segment_timeline --log_file_generation_deletion \&#xA;--mpd_output $OUTPUT/$output_mpd.mpd &amp;&#xA;

    &#xA;

    Looking at the mpd generated as a result of packaging, the duration of the audio is twice that of the video, and the number of segments is half.&#xA;The following is the content of mpd :

    &#xA;

    &lt;?xml version="1.0" encoding="UTF-8"?>&#xA;&#xA;<mpd xmlns="urn:mpeg:dash:schema:mpd:2011" profiles="urn:mpeg:dash:profile:isoff-live:2011" minbuffertime="PT5S" type="dynamic" publishtime="2021-03-23T10:01:57Z" availabilitystarttime="2021-03-23T09:59:55Z" minimumupdateperiod="PT5S" timeshiftbufferdepth="PT40S">&#xA;<period start="PT0S">&#xA;<adaptationset contenttype="audio" segmentalignment="true">&#xA;<representation bandwidth="140020" codecs="mp4a.40.2" mimetype="audio/mp4" audiosamplingrate="48000">&#xA;<audiochannelconfiguration schemeiduri="urn:mpeg:dash:23003:3:audio_channel_configuration:2011" value="2"></audiochannelconfiguration>&#xA;<segmenttemplate timescale="90000" initialization="/home/test/timing_logic/package/audio/0/audio.mp4" media="/home/test/timing_logic/package/audio/0/$Time$.m4a" startnumber="16">&#xA;<segmenttimeline>&#xA;<s t="6751436" d="449280"></s>&#xA;<s t="7200716" d="451200"></s>&#xA;<s t="7651916" d="449280"></s>&#xA;<s t="8101196" d="374400"></s>&#xA;<s t="8551196" d="449280"></s>&#xA;<s t="9000476" d="451200"></s>&#xA;<s t="9451674" d="449280"></s>&#xA;<s t="9900956" d="449280"></s>&#xA;<s t="10350236" d="451200"></s>&#xA;<s t="10801434" d="374400"></s>&#xA;</segmenttimeline>&#xA;</segmenttemplate>&#xA;</representation>&#xA;</adaptationset>&#xA;<adaptationset contenttype="video" width="3840" height="2160" framerate="90000/3600" segmentalignment="true" par="16:9">&#xA;<representation bandwidth="1520392" codecs="hvc1.2.4.L153" mimetype="video/mp4" sar="1:1">&#xA;<segmenttemplate timescale="90000" initialization="/home/test/timing_logic/package/video/0/video.mp4" media="/home/test/timing_logic/package/video/0/$Time$.m4s" startnumber="19">&#xA;<segmenttimeline>&#xA;<s t="16954440" d="900000" r="4"></s>&#xA;</segmenttimeline>&#xA;</segmenttemplate>&#xA;</representation>&#xA;</adaptationset>&#xA;</period>&#xA;</mpd>&#xA;

    &#xA;

    When looking at the MPD, it seems that the shaka packager checks the PTS or DTS of the TS when creating a segment and recording the contents of the SegmentTimeline.&#xA;But I couldn't understand even by looking at the MPEG standard documentation and the DASH-IF documentation.

    &#xA;

    My question is whether the packager refers to PTS or DTS when creating a segment.&#xA;How are SegmentTimeline's S@t and S@d recorded ?&#xA;What algorithm is the SegmentTimeline recorded with ? Please help me. Thank you.

    &#xA;

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