# 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
- 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
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).
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
Added gMock matchers for matching xmlNodePtr and its attributes.
Clean up mpd_unittests to make it easier to separate adaptation set
tests and representation tests.
Change-Id: I31816b06e9c76f92d4a82656c659f3b9acae8cb5
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
- 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
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
Bei Li
Rintaro Kuroiwa