MediaRecorder should support the bitsPerSecond option

• Component: WebRTC
• Status: RESOLVED FIXED

[maxcodefaster]

Referencing https://bugs.webkit.org/show_bug.cgi?id=85851#c92

audioBitesPerSecond, videoBitsPerSecond, bitsPerSecond are not respected by WebKit. This results in huge blobs produced by MediaRecorder, which can not be uploaded.

[youenn fablet]

(In reply to maxcodefaster from comment #0)
> Referencing https://bugs.webkit.org/show_bug.cgi?id=85851#c92
> 
> audioBitesPerSecond, videoBitsPerSecond, bitsPerSecond are not respected by
> WebKit. This results in huge blobs produced by MediaRecorder, which can not
> be uploaded.

audioBitsPerSecond and videoBitsPerSecond should be respected by WebKit.
bitsPerSecond is not supported yet though.

[youenn fablet]

Created attachment 448284 [details]
Patch

[youenn fablet]

Created attachment 448295 [details]
Patch

[Darin Adler]

Comment on attachment 448295 [details]
Patch

View in context: https://bugs.webkit.org/attachment.cgi?id=448295&action=review

> Source/WebCore/Modules/mediarecorder/MediaRecorder.cpp:408
> +    auto rates = MediaRecorderPrivate::computeBitRates(m_options, updateWithStream == UpdateWithStream::Yes ? &m_stream->privateStream() : nullptr);
> +    m_audioBitsPerSecond = rates.first;
> +    m_videoBitsPerSecond = rates.second;

Could do it like this:

    std::tie(m_audioBitsPerSecond, m_videoBitsPerSecond) = MediaRecorderPrivate::computeBitRates(m_options, privateStream);

> Source/WebCore/Modules/mediarecorder/MediaRecorder.h:122
> +    enum class UpdateWithStream { No, Yes };
> +    void updateBitRates(UpdateWithStream);

In a case like this, consider two separate named functions. They can call a internal function that takes a stream pointer. Could even have one take a stream pointer that defaults to null if you want since this is all private.

This gives us the flexibility to come up with two clean names rather than having to name both a function and an enumeration.

> Source/WebCore/platform/mediarecorder/MediaRecorderPrivate.cpp:109
> +        bool hasAudio = stream ? stream->hasAudio() : true;
> +        bool hasVideo = stream ? stream->hasVideo() : true;

I think I personally might find the Boolean logic easier to read than the ? :

    bool hasAudio = !stream || stream->hasAudio();

Not sure which you think is clearer.

> Source/WebCore/platform/mediarecorder/MediaRecorderPrivate.cpp:113
> +            auto audioBitsPerSecond =  std::min(LargeAudioBitRate, std::max(SmallAudioBitRate, totalBitsPerSecond / 10));

Extra space here before the "std::min".

The "/ 10" here seems like a magic number. I don’t understand why it’s there!

> Source/WebCore/platform/mediarecorder/MediaRecorderPrivate.cpp:125
> +    return std::make_pair(options.audioBitsPerSecond.value_or(LargeAudioBitRate), options.videoBitsPerSecond.value_or(LargeVideoBitRate));

Consider the { } syntax instead of std::make_pair.

> Source/WebCore/platform/mediarecorder/MediaRecorderPrivate.h:76
> +    static std::pair<unsigned, unsigned> computeBitRates(const MediaRecorderPrivateOptions&, const MediaStreamPrivate* = nullptr);

Do you think it’s obvious what the two halves of the pair are?

[youenn fablet]

Created attachment 448369 [details]
Patch for landing

[EWS]

Committed r287613 (245740@main): <https://commits.webkit.org/245740@main>

All reviewed patches have been landed. Closing bug and clearing flags on attachment 448369 [details].

[Radar WebKit Bug Importer]

<rdar://problem/87138299>