1041919 - Always use MP4Reader/PDM in MediaSourceDecoder

Status: RESOLVED FIXED

(Core :: Audio/Video, defect)

Description

[Matthew Gregan [:kinetik]]

MP4Reader is hidden behind the prefs media.fragmented-mp4.exposed and media.fragmented-mp4.enabled.  MSE always needs fragmented MP4 support, so change the code that instantiates Readers inside MSE to ignore those prefs and always use MP4Reader.

Note that, on Linux at least, media.fragmented-mp4.ffmpeg.enabled will still need to be set before MP4 decoding will work.

Comment 1

[Matthew Gregan [:kinetik]]

Attachment: Always use MP4Reader/PDM in MediaSourceDecoder.

the alternative was to pass an "is-this-for-MSE/ignore-pref" flag all the
way down into the places where the fmp4 prefs are checked, which seemed
uglier.

Comment 2

[Chris Pearce [:cpearce (Not reading bugmail)]]

Comment on attachment 8460717 [details] [diff] [review]
Always use MP4Reader/PDM in MediaSourceDecoder.

Review of attachment 8460717 [details] [diff] [review]:
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We will at some stage have to signal some (maybe via a parameter to MP4Reader's constructor?) that the MP4Reader needs to enforce the MP4 bitstream constraints required by MSE.

::: content/media/mediasource/MediaSourceDecoder.cpp
@@ +431,5 @@
> +  // PlatformDecoderModules is hidden behind prefs for regular video
> +  // elements, but we always want to use it for MSE, so instantiate it
> +  // directly here.
> +  if (aType.LowerCaseEqualsLiteral("video/mp4") || aType.LowerCaseEqualsLiteral("audio/mp4")) {
> +    MP4Decoder::IsEnabled(); // Ignore result, just forces PDM to initialize.

Include the check for MP4Decoder::IsEnabled() in this if statement, otherwise you'll create the MP4Reader on WinXP when it can't actually decode.

Comment 3

[Matthew Gregan [:kinetik]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/4493663d7cfe

Comment 4

[Carsten Book [:Tomcat]]

https://hg.mozilla.org/mozilla-central/rev/4493663d7cfe