[whatwg] need a way to set output format from StreamRecorder
kevinmarks at gmail.com
Mon Feb 14 22:33:13 PST 2011
On Mon, Feb 14, 2011 at 2:39 PM, Ian Hickson <ian at hixie.ch> wrote:
> On Fri, 19 Nov 2010, Per-Erik Brodin wrote:
> > We are about to start implementing stream.record() and StreamRecorder.
> > The spec currently says that “the file must be in a format supported by
> > the user agent for use in audio and video elements” which is a
> > reasonable restriction. However, there is currently no way to set the
> > output format of the resulting File that you get from recorder.stop().
> > It is unlikely that specifying a default format would be sufficient if
> > you in addition to container formats and codecs consider resolution,
> > color depth, frame rate etc. for video and sample size and rate, number
> > of channels etc. for audio.
> > Perhaps an argument should be added to record() that specifies the
> > output format from StreamRecorder as a MIME type with parameters? Since
> > record() should probably throw when an unsupported type is supplied, it
> > would perhaps be useful to have a canRecordType() or similar to be able
> > to test for supported formats.
> I haven't added anything here yet, mostly because I've no idea what to
> add. The ideal situation here is that we have one codec that everyone can
> read and write and so don't need anything, but that may be hopelessly
That isn't the ideal, as it locks us into the current state of the art
forever. The ideal is to enable multiple codecs +formats that can be swapped
out over time. That said, uncompressed audio is readily codifiable, and we
could pick a common file format, sample rate, bitdepth and channel caount
In the meantime I encourage implementors to experiment with
> this (with all the APIs vendor-prefixed of course) to work out what the
> API should look like. Implementation experience is the main thing that
> will drive this forward, I think.
That is a fair point.
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