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Add preliminary support for applying rewrite rules to the MPD manifest before downloading media
segments. Rewrite rules are expressed as XSLT stylesheets that are applied to the manifest using
thexsltproccommandline tool (which supports XSLT v1.0). This allows complex rewrite rules to
be expressed using a standard (if a little finicky) stylesheet language. See the--xslt-stylesheet
commandline option.This functionality and API are experimental, and may evolve to use a different XSLT processor, such as
Saxon-HE (https://github.com/Saxonica/Saxon-HE/) which has support for XSLT v3.0, but is
implemented in Java. Alternatively, a more general filtering functionality based on WASM bytecode
might be implemented to allow the implementation of rewrite rules in a range of languages that can
compile to WebAssembly. -
Change the default ordering of muxer applications when saving media to a .webm container to prefer
VLC over ffmpeg. With the commandline arguments that we use, ffmpeg does not automatically
reencode content to a codec that is allowed by the WebM specification, whereas VLC does do so. -
Some limited DASH conformity checks will be run on manifests before downloading, which may
generate warnings written to stderr. A surprising number of manifests, including some
generated by the most widely used commercial streaming software, feature non-conformities such as
incorrect values of @MaxWidth / @maxHeight or inserted advertising segments that don't respect
@maxSegmentDuration).