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• What does "dash" - mean as ffmpeg output filename

  26 août 2020, par DDS

  I'm trying to use ffmpeg with gnuplot to draw some audio spectra, I'm following this ffmpeg doc link.

  


  Now I'm asking what "dash" - means on this line right after -f data, it should be a filename : the last element of ffmpeg command should the output file but I have no files named - in the directory after running the command.

  


  ffmpeg -y -i in.wav -ac 1 -filter:a aresample=8000 -map 0:a -c:a pcm_s16le -f data - | gnuplot -p -e "plot 'code>

  


  I looked on ffmpeg docs but I didn't find anything.

  


• 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;

  


  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.

  


• avformat/dashdec : add dash demuxer base version

  9 septembre 2017, par Steven Liu

  avformat/dashdec : add dash demuxer base version
  ffmpeg need a dash demuxer for demux the dash formats base on
  
  https://github.com/samsamsam-iptvplayer/exteplayer3/blob/master/tmp/ffmpeg/patches/3.2.2/000001_add_dash_demux.patch
  TODO :
  
  1. support multi bitrate dash.
  v2 fixed :
  
  1. from autodetect to disabled
  
  2. from camelCase code style to ffmpeg code style
  
  3. from RepType to AVMediaType
  
  4. fix variable typo
  
  5. change time value from uint32_t to uint64_t
  
  6. removed be used once API
  
  7. change 'time(NULL)`, except it is not 2038-safe.' to av_gettime and av_timegm
  
  8. merge complex free operation to free_fragment
  
  9. use API from snprintf to av_asprintf
  v3 fixed :
  
  1. fix typo from —enabled-xml2 to —enable-xml2
  v4 fixed :
  
  1. from —enable-xml2 to —enable-libxml2
  
  2. move system includes to top
  
  3. remove nouse includes
  
  4. rename enum name
  
  5. add a trailing comma for the last entry enum
  
  6. fix comment typo
  
  7. add const to DASHContext class front
  
  8. check sscanf if return arguments and give warning message when error
  
  9. check validity before free seg->url and seg
  
  10. check if the val is null, before use atoll
  v5 fixed :
  
  1. fix typo from mainifest to manifest
  v6 fixed :
  
  1. from realloc to av_realloc
  
  2. from free to av_free
  v7 fixed :
  
  1. remove the -lxml2 from configure when require_pkg_config
  v8 fixed :
  
  1. fix replace filename template by av_asprintf secure problem
  v9 modified :
  
  1. make manifest parser clearly
  v10 fixed :
  
  1. fix function API name code style
  
  2. remove redundant strreplace call
  
  3. remove redundant memory operation and check return value from get_content_url()
  
  4. add space between ) and 
  
  5. remove no need to log the value for print
  
  v11 fixed :
  
  1. from atoll to strtoll
  
  Suggested-by : Michael Niedermayer <michael@niedermayer.cc>
  v12 fixed :
  
  1. remove strreplace and instead by av_strreplace
  
  Suggested-by : Nicolas George <george@nsup.org>
  v13 fixed :
  
  1. fix bug : cannot play :
  
  http://dash.edgesuite.net/akamai/bbb_30fps/bbb_30fps.mpd
  
  Reported-by : Andy Furniss <adf.lists@gmail.com>
  v14 fixed :
  
  1. fix bug : TLS connection was non-properly terminated
  
  2. fix bug : No trailing CRLF found in HTTP header
  
  Reported-by : Andy Furniss <adf.lists@gmail.com>
  v15 fixed :
  
  1. play youtube link : ffmpeg -i $(youtube-dl -J "https://www.youtube.com/watch?v=XmL19DOP_Ls" ; | jq -r ".requested_formats[0].manifest_url")
  
  2. code refine for timeline living stream
  
  Reported-by : Ricardo Constantino <wiiaboo@gmail.com>
  v16 fixed :
  
  1. remove the snprintf and instead by get_segment_filename make safety
  
  2. remove unnecessary loops
  
  3. updated xmlStrcmp and xmlFree to av_* functions
  
  4. merge code repeat into one function
  
  5. add memory alloc faild check
  
  6. update update_init_section and open_url
  
  7. output safety error message when filename template not safe
  
  Suggested-by : wm4 <nfxjfg@googlemail.com>
  v17 fixed :
  
  1. add memory alloc faild check
  
  2. fix resource space error at free_representation
  v18 fixed :
  
  1. add condition of template format
  v19 fixed :
  
  1. fix typo of the option describe
  v20 fixed :
  
  1. add the c->base_url alloc check
  
  2. make the DASHTmplId same to dashenc
  v21 fixed :
  
  1. remove get_repl_pattern_and_format and get_segment_filename
  
  2. process use dashcomm APIs
  v22 fixed :
  
  1. modify the include "dashcomm.h" to include "dash.h"
  
  2. use internal API from dash_fill_tmpl_params to ff_dash_fill_tmpl_params
  Signed-off-by : Steven Liu <lq@onvideo.cn>
  
  Signed-off-by : samsamsam <samsamsam@o2.pl>
  

  • [DH] configure
  • [DH] libavformat/Makefile
  • [DH] libavformat/allformats.c
  • [DH] libavformat/dashdec.c