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Granite de l’Aber Ildut
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Mis à jour : Septembre 2011
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Algorithm when recording SegmentTimeline of MPEG-DASH MPD in shaka packager
25 mars 2021, par jgkim0518I 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 :


<?xml version="1.0" encoding="UTF-8"?>

<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">
<period start="PT0S">
<adaptationset contenttype="audio" segmentalignment="true">
<representation bandwidth="140020" codecs="mp4a.40.2" mimetype="audio/mp4" audiosamplingrate="48000">
<audiochannelconfiguration schemeiduri="urn:mpeg:dash:23003:3:audio_channel_configuration:2011" value="2"></audiochannelconfiguration>
<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">
<segmenttimeline>
<s t="6751436" d="449280"></s>
<s t="7200716" d="451200"></s>
<s t="7651916" d="449280"></s>
<s t="8101196" d="374400"></s>
<s t="8551196" d="449280"></s>
<s t="9000476" d="451200"></s>
<s t="9451674" d="449280"></s>
<s t="9900956" d="449280"></s>
<s t="10350236" d="451200"></s>
<s t="10801434" d="374400"></s>
</segmenttimeline>
</segmenttemplate>
</representation>
</adaptationset>
<adaptationset contenttype="video" width="3840" height="2160" framerate="90000/3600" segmentalignment="true" par="16:9">
<representation bandwidth="1520392" codecs="hvc1.2.4.L153" mimetype="video/mp4" sar="1:1">
<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">
<segmenttimeline>
<s t="16954440" d="900000" r="4"></s>
</segmenttimeline>
</segmenttemplate>
</representation>
</adaptationset>
</period>
</mpd>


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.
But I couldn't understand even by looking at the MPEG standard documentation and the DASH-IF documentation.


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


-
ffmpeg creates empty mpd-file
1er avril 2021, par MacsterI'm trying to live stream a webm file using ffmpeg and Dash.js as a Player. Creating chunks with ffmpeg seems to work fine, but when want to create the manifest it says
Could not find codec parameters for stream 0 (Video: vp9, none, 640x480): unspecified pixel format Consider increasing the value for the 'analyzeduration' and 'probesize' optionsand at the endOutput file is empty, nothing was encoded (check -ss / -t / -frames parameters if used).

Commands I use


ffmpeg -re -r 25 -i Dash/strm.webm
 -map 0:v:0
 -pix_fmt yuv420p
 -c:v libvpx-vp9
 -s 640x480 -keyint_min 25 -g 25 
 -speed 6 -threads 8 -static-thresh 0 -max-intra-rate 300 
 -deadline realtime -lag-in-frames 0 -error-resilient 1
 -f webm_chunk 
 -header "Dash/glass_360.hdr"
 -chunk_start_index 1
 Dash\glass_360_%d.chk


Manifest


ffmpeg ^
 -f webm_dash_manifest -live 1
 -r 25
 -i Dash/glass_360.hdr
 -c copy
 -map 0
 -r 25
 -framerate 25
 -f webm_dash_manifest -live 1
 -adaptation_sets "id=0,streams=0"
 -chunk_start_index 1
 -chunk_duration_ms 1000
 -time_shift_buffer_depth 7200
 -minimum_update_period 7200
 Dash/glass_live_manifest.mpd


Manifest Output


libavutil 56. 49.100 / 56. 49.100
 libavcodec 58. 87.101 / 58. 87.101
 libavformat 58. 43.100 / 58. 43.100
 libavdevice 58. 9.103 / 58. 9.103
 libavfilter 7. 83.100 / 7. 83.100
 libswscale 5. 6.101 / 5. 6.101
 libswresample 3. 6.100 / 3. 6.100
 libpostproc 55. 6.100 / 55. 6.100
[webm_dash_manifest @ 0000015f19f2ea40] Could not find codec parameters for stream 0 (Video: vp9, none, 640x480): unspecified pixel format
Consider increasing the value for the 'analyzeduration' and 'probesize' options
Input #0, webm_dash_manifest, from 'Dash/glass_360.hdr':
 Metadata:
 ENCODER : Lavf58.43.100
 Duration: N/A, bitrate: N/A
 Stream #0:0(eng): Video: vp9, none, 640x480, SAR 1:1 DAR 4:3, 1k tbr, 1k tbn, 1k tbc (default)
 Metadata:
 ALPHA_MODE : 1
 ENCODER : Lavc58.87.101 libvpx-vp9
 webm_dash_manifest_file_name: glass_360.hdr
 webm_dash_manifest_track_number: 1
Output #0, webm_dash_manifest, to 'stream_manifest.mpd':
 Metadata:
 encoder : Lavf58.43.100
 Stream #0:0(eng): Video: vp9, none, 640x480 [SAR 1:1 DAR 4:3], q=2-31, 1k tbr, 1k tbn, 1k tbc (default)
 Metadata:
 ALPHA_MODE : 1
 ENCODER : Lavc58.87.101 libvpx-vp9
 webm_dash_manifest_file_name: glass_360.hdr
 webm_dash_manifest_track_number: 1
Stream mapping:
 Stream #0:0 -> #0:0 (copy)
Press [q] to stop, [?] for help
frame= 0 fps=0.0 q=-1.0 Lsize= 1kB time=00:00:00.00 bitrate=N/A speed= 0x
video:0kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown
Output file is empty, nothing was encoded (check -ss / -t / -frames parameters if used)


glass_live_manifest.mpd


<?xml version="1.0" encoding="UTF-8"?>

<period start="PT0S">
<adaptationset mimetype="video/webm" codecs="vp9" lang="eng" bitstreamswitching="true" subsegmentalignment="true" subsegmentstartswithsap="1">
<contentcomponent type="video"></contentcomponent>
<segmenttemplate timescale="1000" duration="1000" media="glass_$RepresentationID$_$Number$.chk" startnumber="1" initialization="glass_$RepresentationID$.hdr"></segmenttemplate>
<representation bandwidth="1000000" width="640" height="480" codecs="vp9" mimetype="video/webm" startswithsap="1"></representation>
</adaptationset>
</period>



UPDATE


I fixed the "warnings" by changing the comands like this :


ffmpeg -re -r 25 -i Dash/strm.webm
-map 0:v:0
-pix_fmt yuv420p
-c:v libvpx
-s 640x480 -keyint_min 60 -g 60 -speed 6 -tile-columns 4 -frame-parallel 1 -threads 8 -static-thresh 0 -max-intra-rate 300 -deadline realtime -lag-in-frames 0 -error-resilient 1
-b:v 3000k
-f webm_chunk
-header "Dash/glass_360.hdr"
-chunk_start_index 1 Dash/glass_360_%d.chk
-map 0:a:0
-c:a libvorbis
-b:a 128k -ar 44100
-f webm_chunk
-audio_chunk_duration 2000
-header Dash/glass_171.hdr
-chunk_start_index 1 Dash/glass_171_%d.chk

ffmpeg
-f webm_dash_manifest -live 1
-i Dash/glass_360.hdr
-f webm_dash_manifest -live 1
-i Dash/glass_171.hdr
-c copy
-map 0 -map 1
-f webm_dash_manifest -live 1
-adaptation_sets "id=0,streams=0 id=1,streams=1"
-chunk_start_index 1
-chunk_duration_ms 2000
-time_shift_buffer_depth 7200
-minimum_update_period 7200 Dash/glass_video_manifest.mpd


However, it's still not working.


-
Algorithm when recording SegmentTimeline
24 mars 2021, par jgkim0518I 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 :


<?xml version="1.0" encoding="UTF-8"?>

<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">
<period start="PT0S">
<adaptationset contenttype="audio" segmentalignment="true">
<representation bandwidth="140020" codecs="mp4a.40.2" mimetype="audio/mp4" audiosamplingrate="48000">
<audiochannelconfiguration schemeiduri="urn:mpeg:dash:23003:3:audio_channel_configuration:2011" value="2"></audiochannelconfiguration>
<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">
<segmenttimeline>
<s t="6751436" d="449280"></s>
<s t="7200716" d="451200"></s>
<s t="7651916" d="449280"></s>
<s t="8101196" d="374400"></s>
<s t="8551196" d="449280"></s>
<s t="9000476" d="451200"></s>
<s t="9451674" d="449280"></s>
<s t="9900956" d="449280"></s>
<s t="10350236" d="451200"></s>
<s t="10801434" d="374400"></s>
</segmenttimeline>
</segmenttemplate>
</representation>
</adaptationset>
<adaptationset contenttype="video" width="3840" height="2160" framerate="90000/3600" segmentalignment="true" par="16:9">
<representation bandwidth="1520392" codecs="hvc1.2.4.L153" mimetype="video/mp4" sar="1:1">
<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">
<segmenttimeline>
<s t="16954440" d="900000" r="4"></s>
</segmenttimeline>
</segmenttemplate>
</representation>
</adaptationset>
</period>
</mpd>


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.
But I couldn't understand even by looking at the MPEG standard documentation and the DASH-IF documentation.


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


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