Disable the NBest Subtitle track for ShakaPackager #181
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Description: The NBest track wtih .vtt file is not directly used by our AMS origin server today, and the cues inside the vtt file might be in wrong order in some cases. This change just disable the NBest track when ShakaPackager is used to generate DASH/HLS manifests. For LiveToVOD asset, the track with .vtt as its source is treated as NBest track. For asset generated by MES Copy job, it may generate multiple text tracks with .cmft file which are generated from the .vtt files, In this case, keep one CMFT track for each language, the one with the biggest vtt file size is used for that language, other close caption tracks are not used for ShakaPackager. Even though those vtt files are not used by ShakaPackager, but the cue timestamps are still adjusted to match with new audio/video timelines, and the updated vtt files are copied over to the destination folder for the asset owner to consume them with other tools. The change keep uses the current design, and extend it by using the settings of the matching Manifiest item in the Manifest list, if the match track is not used by the ShakaPackager, the value of Manifest list for that track is set to "", so that the packager knows how to deal with it. The change also contains a minor fix where it always uploaded the .vtt files in advance when the asset contains cmft file as track source which are generated from .vtt file, since the vtt files are updated and used by ShakaPackager, the pre-uploading should not directly upload vtt files for this asset.
weibz
requested review from
duggaraju,
pohhsu,
BruceLin-MS and
melindawangmsft
pohhsu
approved these changes
Sep 14, 2023
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Description:
The NBest track wtih .vtt file is not directly used by our AMS origin server today,
and the cues inside the vtt file might be in wrong order in some cases.
This change just disable the NBest track when ShakaPackager is used to generate DASH/HLS manifests.
For LiveToVOD asset, the track with .vtt as its source is treated as NBest track.
For asset generated by MES Copy job, it may generate multiple text tracks with .cmft file which are generated from the .vtt files,
In this case, keep one CMFT track for each language, the one with the biggest vtt file size is used for that language, other close caption tracks are not used for ShakaPackager.
Even though those vtt files are not used by ShakaPackager, but the cue timestamps are still adjusted to match with new audio/video timelines, and the updated vtt files are copied over to the destination folder
for the asset owner to consume them with other tools.
The change keep uses the current design, and extend it by using the settings of the matching Manifiest item in the Manifest list, if the match track is not used
by the ShakaPackager, the value of Manifest list for that track is set to "", so that the packager knows how to deal with it.
The change also contains a minor fix where it always uploaded the .vtt files in advance when the asset contains cmft file as track source which are generated from .vtt file,
since the vtt files are updated and used by ShakaPackager, the pre-uploading should not directly upload vtt files for this asset.