# Low Latency DASH - `availabilityTimeComplete=false`
Low Latency DASH manifests generated by Packager were missing the
attribute `availabilityTimeComplete`. As per the [DASH
specs](https://dashif.org/docs/CR-Low-Latency-Live-r8.pdf):
**_the AdaptationSet@availabilityTimeCompleteshould be present and be
set to 'FALSE'_**
## The Issue
The missing attribute caused ULL streams from Shaka Packager to no
longer be compatible with DASH.js. Previous versions of DASH.js allowed
users to specify ULL mode when initializing the player. However, the
most recent releases of DASH.js automatically detect ULL by scanning the
manifest for ULL specific attributes. Although there are many attributes
only associated with ULL, [DASH.js only greps for
`availabilityTimeComplete` in its detection
logic](https://github.com/Dash-Industry-Forum/dash.js/blob/development/src/streaming/controllers/PlaybackController.js#L792-L805).
Because of the missing attribute in Packager and the limited ULL
verification criteria by DASH.js, Packager streams were not being
treated as low latency streams by DASH.js.
## Testing
### Unit Testing
`./mpd_unittest
--gtest_filter="SegmentTemplateTest.OneSegmentLowLatency"`
` ./mpd_unittest
--gtest_filter="LowLatencySegmentTest.LowLatencySegmentTemplate"`
### Manual Testing
- Created a low latency stream with Shaka Packager
- Observed the expected `availabilityTimeComplete=false` attribute in
the generated DASH manifest.
# LL-DASH Support
These changes add support for LL-DASH streaming.
**NOTE:** LL-HLS support is still in progress, but it's coming. :)
## Testing
`./chunking_unittest --gtest_filter="ChunkingHandlerTest.LowLatencyDash"`
`./media_event_unittest --gtest_filter="MpdNotifyMuxerListenerTest.LowLatencyDash"`
`./mpd_unittest --gtest_filter="PeriodTest.LowLatencyDashMpdGetXml"`
`./mpd_unittest --gtest_filter="SimpleMpdNotifierTest.NotifyAvailabilityTimeOffset"`
`./mpd_unittest --gtest_filter="SimpleMpdNotifierTest.NotifySegmentDuration"`
`./mpd_unittest --gtest_filter="LowLatencySegmentTest.LowLatencySegmentTemplate"`
Note, packager_test must be run from the main project directory
`./out/Release/packager_test --gtest_filter="PackagerTest.LowLatencyDashEnabledAndUtcTimingNotSet"`
`./out/Release/packager_test --gtest_filter="PackagerTest.LowLatencyDashEnabledAndUtcTimingNotSet"`
This converts all time parameters to signed, finishing a cleanup that
was started in 2018 in b4256bf0. This changes the type of:
- timestamps
- PTS specifically
- timestamp offsets
- timescales
- durations
This excludes:
- MP4 box definitions
- DTS specifically
This is meant to address signed/unsigned conversion issues on arm64
that caused some test cases to fail.
Change-Id: Ic752a20cbc6e31fea6bc0894d1771833171e7cbe
This allows us to have presentationTimeOffset for text streams since
this needs to appear on a SegmentList/SegmentBase/SegmentTemplate.
Issue #832
Change-Id: Id3ab3308029185815d50a6cb1142e6a97f744d4f
This only supports TTML output; meaning the user can convert WebVTT
into TTML, but not the other way around. This will be useful for
DVB-sub subtitles that would be better supported within TTML.
This only adds text-based output; a follow-up will add MP4 support.
Change-Id: I0944b7df95d7765e55f203fc5e9a644f5c455dd8
- Use std::move to transfer ownership.
- Avoid libxml primitives outside XmlNode.
- Have attribute setting return errors.
- Mark bool returns with WARN_UNUSED_RESULTS and use return value.
- Use std::string over char*.
Change-Id: Ia00bb29c690025275e270f10e5c065722481c0c5
Now text-based WebVTT also uses the generic media pipeline. This
converts the WebVttTextOutputHandler to a WebVttMuxer to be more
consistent with the other muxer types.
This also allows choosing between single-segment text and multi-segment.
Before, we would generate both and use single-segment for DASH and
multi-segment for HLS; but now you can choose between either and either
are supported in both DASH and HLS.
Change-Id: I6f7edda09e01b5f40e819290d3fe6e88677018d9
Per https://dashif.org/docs/DASH-IF-IOP-v4.3.pdf 4.4.3.6 Signalling the last segment number in Period, there are three ways to signal the last segment number:
a. Use the lmsg signalling as defined in clause 4.4.3.5.
b. Use the Segment Timeline with @r value greater or equal to 0.
c. Add a Supplemental Descriptor with @schemeIdUri set to http://dashif.org/guidelines/last-segment-number with the @value set to the last segment number.
We do not support (a). This change adds support for (c) when Segment Timeline (b) is not used, i.e. when Representation has constant duration (could be approximate).
Under flag --dash_add_last_segment_number_when_needed (disabled by default).
Add dash_accessibilities stream descriptor, which is a semi-colon
separated list of accessibility_scheme_id_uri=value. It is optional.
Add dash_roles stream descriptor, which is a semi-colon separated
list of strings. It is optional.
Closes#565.
Change-Id: Idb1c20bb410fdd016db07e11fe507c102a3dd8ea
Only Marlin Adaptive Streaming Specification – Simple Profile is
supported.
Two additional updates:
- Remove FairPlay ContentProtection element from DASH mpd as FairPlay
does not define a signaling in DASH.
- Updated end to end test to include all DRMs we support.
Closes#381.
Change-Id: Id12269b471ea34983b782cbd92f687332292ef59
It is not always possible to align segment duration to target duration
exactly. For example, for AAC with sampling rate of 44100, there are
always 1024 audio frames per sample, so the sample duration is
1024/44100. For a target duration of 2 seconds, the closest segment
duration would be 1.984 or 2.00533.
This feature allows MPD generator to treat these segments as having
the same duration, thus allows MPD generator to generate less
SegmentTimeline entries and potentially no SegmentTimeline entries
(replaced with SegmentTemplate@duration instead if
--segment_template_constant_duration flag is enabled).
Under flag --allow_approximate_segment_timeline. Disabled by default.
Fixes#330.
Change-Id: I5044eaa348ebbf45bf792a2af53fc95a115ae21b
The file_name fields will be used to solely indicate file paths on the
designated file system, and they are used to do normal file operations,
including file creation, file updating and file removal if needed;
added new xxx_url fields, for the URLs that should appear on DASH
manifest or HLS playlists.
xxx_url are the URIs of the media in the manifest. The fields are
converted from file_name fields but adjusted to be relative to DASH
manifest path or HLS playlist path, optionally with base_url prepended.
Previously the file_name fields are converted in place to indicate
URLs when passing to manifest / playlist builders. The original file
names were lost, which made it difficult to remove files outside of
live window.
Now that the input file names are preserved. File system APIs can
operate on the original file names while manifest / playlist generation
functions can operate on URLs.
Issue: #233
Change-Id: I36a64f16e3d1261ce91783a86588f24ad1371662
Chrome internally uses time accurate to microseconds, which is
implemented per MSE spec (https://www.w3.org/TR/media-source/).
Generate Period@duration with better precision to avoid possible
buffered range gaps in Chrome (possibly other browsers too), which
may lead to other problems like playback stall.
b/74238961
Fixes#368.
Change-Id: I357a0f62b67f75c7ca044bb99ea4e3c8bbb6fecd
Current mechanism of using AdaptationSet @group is not spec compliant.
The spec compliant mechanism is to use supplemental descriptor with
schemeIdUri: urn:mpeg:dash:adaptation-set-switching:2016 as specified
in ISO/IEC 23009-1:2014/Amd.4:2016.
Fixes#156
Change-Id: I4d97648547a23315ba9c09dcadb14e18c99a45fc
1. Replace STLDeleter with unique_ptr in container, which is
supported in C++11
2. Replace string_as_array with &string[0] which is guaranteed
to work in C++11
Change-Id: I7f39c0e51fc8a3fcbb41313094a0ca6b33db7bf3
Parse channel layout value from dec3 box. Pass it through audio stream
info. MPD builder forms audio channel configuration to signal ec-3
codec.
Specs: 1) ETSI TS 102 366 V1.3.1 Digital Audio Compression (AC-3,
Enhanced AC-3) Standard E.1.3.1.8.
2) DASH-IF Interoperability Points v3.0 9.2.1.2.
Issue #64
Change-Id: Ia2c22dd3d82e757ba5a88ba1de35c5d593f5005e
- @width, @height, @frameRate for Representation element will not be
set if the attributes are set at AdaptationSet level.
Issue #55
Change-Id: Ib4e669142874f9e8f0ca773df9f87a3fef01b729
- ContentProtection elements should be added explicitly by the
AddContentProtection() methods.
- This is because some MPDs should have ContentProtection at
AdaptationSet level instead of Representation.
- Change SimpleMpdNotifier, which uses MpdBuilder, to add
ContentProtectionElements. The logic is moved from MuxerListener.
- Add Element class for specifying subelements for
ContentProtectionElement.
Change-Id: I9bedfb3e5a5ac0b3d5c702f1e6e4a8608c978d1d
- Pass pixel_height and pixel_width from VideoStreamInfo to MediaInfo.
- par can only be set if all the Representations have the same
picture aspect ratio. That is the ratio of sar_x*width:sar_y*height
should all be the same.
- If there is a Representation that does not have the sar attribute set,
par is also not set.
Change-Id: Id34c95e4a99da9ce028a9f35737cfe5bca9e5697
- The fields used to be repeated but there is no use case at the moment.
- DASH IOP explicitly disallows segments with multiple tracks.
Change-Id: Ia0af2048210c546dfaa178735605a81052ea1123
This is a follow up to previous CL.
Generated using command:
find {media,app,mpd} -type f -exec sed -r -i 's/#include "(.*)"/#include
"packager\/\1"/' {} \;
common.gypi and mpd.gyp are also modified to take the path change into
consideration.
Change-Id: I1fb102b4eb73ae5fde5f4ab303a12cec09b05c33
Caitlin O'Callaghan
Joey Parrish
Samidh
Jacob Trimble
Weiguo Shao
sr90
KongQun Yang
Haoming Chen
Bei Li
Rintaro Kuroiwa