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Define AudioDataCopyToOptions with frameOffset and frameCount #228

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Merged
chcunningham merged 7 commits into from
May 26, 2021
Merged

Define AudioDataCopyToOptions with frameOffset and frameCount #228

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941ac31
Define AudioDataCopyToOptions with frameOffset and frameCount
chcunningham May 6, 2021
108935a
Fix typos
chcunningham May 6, 2021
7aaa2e3
Merge remote-tracking branch 'origin/main' into audiodata_readpcm
chcunningham May 21, 2021
6f771e4
Address AudioData copyTo() feedback
chcunningham May 21, 2021
d348baf
Fix frame count computation for interleaved AudioSampleFormats
chcunningham May 25, 2021
9302755
Merge remote-tracking branch 'origin/main' into audiodata_readpcm
chcunningham May 25, 2021
c2a1c9c
Merge remote-tracking branch 'origin/main' into audiodata_readpcm
chcunningham May 26, 2021
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86 changes: 47 additions & 39 deletions index.src.html
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Original file line number Diff line number Diff line change
Expand Up @@ -1957,10 +1957,10 @@
readonly attribute float sampleRate;
readonly attribute unsigned long numberOfFrames;
readonly attribute unsigned long numberOfChannels;
readonly attribute unsigned long byteLength;
readonly attribute unsigned long long duration;
readonly attribute unsigned long long timestamp;
readonly attribute long long duration; // microseconds
readonly attribute long long timestamp; // microseconds

unsigned long byteLength(AudioDataCopyToOptions options);
undefined copyTo([AllowShared] BufferSource destination, AudioDataCopyToOptions options);
AudioData clone();
undefined close();
Expand Down Expand Up @@ -2048,17 +2048,6 @@
The {{AudioData/numberOfChannels}} getter steps are to return
{{AudioData/[[number of channels]]}}.

: <dfn attribute for=AudioData>byteLength</dfn>
:: The the number of bytes allocated to hold all of the samples in this
{{AudioData}}.

The {{AudioData/byteLength}} getter steps are to:
1. Let |sampleSize| be the number of bytes per sample, as defined by the
{{AudioData/[[sample format]]}}.
2. Return the product of multiplying |sampleSize| by
{{AudioData/[[number of channels]]}} and
{{AudioData/[[number of frames]]}}.

: <dfn attribute for=AudioData>timestamp</dfn>
:: The presentation timestamp, in microseconds, for this {{AudioData}}.

Expand All @@ -2075,37 +2064,37 @@
3. Return the product of |durationInSeconds| and |microsecondsPerSecond|.

### Methods ###{#audiodata-methods}
: <dfn method for=AudioData>
copyTo(|destination|, |options|)
</dfn>
: <dfn method for=AudioData>byteLength(|options|)</dfn>
:: Returns the number of bytes required to hold the samples as described by
|options|.

When invoked, run these steps:
1. Let |copyFrameCount| be the result of running the
[=Compute Copy Frame Count=] algorithm with |options|.
2. Let |bytesPerSample| be the number of bytes per sample, as defined by
the {{AudioData/[[sample format]]}}.
3. Return the product of multiplying |bytesPerSample| by |copyFrameCount|.

: <dfn method for=AudioData>copyTo(|destination|, |options|)</dfn>
:: Copies the samples from the specified plane of the {{AudioData}} to the
destination buffer.

When invoked, run these steps:
1. If the value of |frame|'s {{AudioData/[[detached]]}} internal slot is
`true`, throw an {{InvalidStateError}} {{DOMException}}.
2. Let |frameCount| be the number of frames in each plane of this
{{AudioData}}'s' [=media resource=], as defined by the getter steps of
{{AudioData/numberOfFrames}}.
3. If |options|.{{AudioDataCopyToOptions/frameOffset}} is greater than or
equal to |frameCount|, throw a {{RangeError}}.
4. Let |copyFrameCount| be the difference of subtracting
|options|.{{AudioDataCopyToOptions/frameOffset}} from |frameCount|.
5. If |options|.{{AudioDataCopyToOptions/frameCount}} [=map/exists=]:
1. If |options|.{{AudioDataCopyToOptions/frameCount}} is greater than
|copyFrameCount|, throw a {{RangeError}}.
2. Otherwise, assign |options|.{{AudioDataCopyToOptions/frameCount}}
to |copyFrameCount|.
6. Let |bytesPerSample| be the number of bytes per sample, as defined by
2. Let |copyFrameCount| be the result of running the
[=Compute Copy Frame Count=] algorithm with |options|.
3. Let |bytesPerSample| be the number of bytes per sample, as defined by
the {{AudioData/[[sample format]]}}.
7. If the product of multiplying |bytesPerSample| by |copyFrameCount| is
4. If the product of multiplying |bytesPerSample| by |copyFrameCount| is
greater than `destination.byteLength`, throw a {{RangeError}}.
8. Let |resource| be the [=media resource=] referenced by
5. Let |resource| be the [=media resource=] referenced by
{{AudioData/[[resource reference]]}}.
9. Let |planeFrames| be the region of |resource| corresponding to
|options|.{{AudioDataCopyToOptions/planeNumber}}.
10. Copy frames of |planeFrames| into |destination|, starting with the
byte positioned at |options|.{{AudioDataCopyToOptions/frameOffset}} and stopping after |copyFrameCount| frames have been copied.
6. Let |planeFrames| be the region of |resource| corresponding to
|options|.{{AudioDataCopyToOptions/planeIndex}}.
7. Copy frames of |planeFrames| into |destination|, starting with the
frame positioned at |options|.{{AudioDataCopyToOptions/frameOffset}}
and stopping after |copyFrameCount| frames have been copied.

: <dfn method for=AudioData>clone()</dfn>
:: Creates a new AudioData with a reference to the same [=media resource=].
Expand All @@ -2126,6 +2115,25 @@

### Algorithms ### {#audiodata-algorithms}

: <dfn>Compute Copy Frame Count</dfn> (with |options|)
:: Run these steps:
1. Let |frameCount| be the number of frames in the plane identified by
|options|.{{AudioDataCopyToOptions/planeIndex}}.

NOTE: For interleaved formats with a single plane, |frameCount| will
be the total number of frames accross all channels.
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@padenot padenot May 21, 2021

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It's the sample count then, if it's across all channels. A frame count is specifically channel-count independent.

This steps should be about finding a number of elements to copy, based on the various parameters passed as parameter. Then the caller simply copies.

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@chcunningham chcunningham May 25, 2021

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Thanks, hopefully fixed! Algo now returns number of elements, including multiplication by channel count for interleaved formats.


2. If |options|.{{AudioDataCopyToOptions/frameOffset}} is greater than or
equal to |frameCount|, throw a {{RangeError}}.
3. Let |copyFrameCount| be the difference of subtracting
|options|.{{AudioDataCopyToOptions/frameOffset}} from |frameCount|.
4. If |options|.{{AudioDataCopyToOptions/frameCount}} [=map/exists=]:
1. If |options|.{{AudioDataCopyToOptions/frameCount}} is greater than
|copyFrameCount|, throw a {{RangeError}}.
2. Otherwise, assign |options|.{{AudioDataCopyToOptions/frameCount}}
to |copyFrameCount|.
5. return |copyFrameCount|.

: <dfn>Clone AudioData</dfn> (with |data|)
:: Run these steps:
1. Let |clone| be a new {{AudioData}} initialized as follows:
Expand All @@ -2145,14 +2153,14 @@

<xmp class='idl'>
dictionary AudioDataCopyToOptions {
required unsigned long planeNumber;
required unsigned long planeIndex;
unsigned long frameOffset = 0;
unsigned long frameCount;
};
</xmp>

: <dfn dict-member for=AudioDataCopyToOptions>planeNumber</dfn>
:: The number identifying the plane to copy from.
: <dfn dict-member for=AudioDataCopyToOptions>planeIndex</dfn>
:: The index identifying the plane to copy from.

: <dfn dict-member for=AudioDataCopyToOptions>frameOffset</dfn>
:: An offset into the source plane data indicating which frame to begin
Expand Down