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fix: Do not scale width by sarRatio, we already generate a pasp box with sarRatio information. #393

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merged 5 commits into from
Jul 14, 2021
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fix: Do not scale width by sarRatio, we already generate a pasp box with sarRatio information. #393

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e2113ca
fix: do not scale width by sarRatio
brandonocasey Jul 13, 2021
4564ba8
more small changes
brandonocasey Jul 13, 2021
92232eb
fix tests, add a comment
brandonocasey Jul 13, 2021
d05e056
clarify comment
brandonocasey Jul 13, 2021
5ac2046
change hex nalUnitType to nalUnitTypeCode
brandonocasey Jul 13, 2021
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14 changes: 9 additions & 5 deletions lib/codecs/h264.js
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Original file line number Diff line number Diff line change
Expand Up @@ -150,6 +150,9 @@ PROFILES_WITH_OPTIONAL_SPS_DATA = {
86: true,
118: true,
128: true,

// TODO: the three profiles below don't
// appear to have sps data in the specificiation anymore?
138: true,
139: true,
134: true
Expand Down Expand Up @@ -210,10 +213,11 @@ H264Stream = function() {
trackId: trackId,
pts: currentPts,
dts: currentDts,
data: data
data: data,
nalUnitTypeCode: data[0] & 0x1f
};

switch (data[0] & 0x1f) {
switch (event.nalUnitTypeCode) {
case 0x05:
event.nalUnitType = 'slice_layer_without_partitioning_rbsp_idr';
break;
Expand All @@ -232,7 +236,6 @@ H264Stream = function() {
case 0x09:
event.nalUnitType = 'access_unit_delimiter_rbsp';
break;

default:
break;
}
Expand Down Expand Up @@ -365,7 +368,7 @@ H264Stream = function() {
picHeightInMapUnitsMinus1,
frameMbsOnlyFlag,
scalingListCount,
sarRatio,
sarRatio = [1, 1],
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default to a 1 to 1 aspect ratio, ie width and height are exact values.

aspectRatioIdc,
i;

Expand Down Expand Up @@ -470,8 +473,9 @@ H264Stream = function() {
profileIdc: profileIdc,
levelIdc: levelIdc,
profileCompatibility: profileCompatibility,
width: Math.ceil((((picWidthInMbsMinus1 + 1) * 16) - frameCropLeftOffset * 2 - frameCropRightOffset * 2) * sarScale),
width: (((picWidthInMbsMinus1 + 1) * 16) - frameCropLeftOffset * 2 - frameCropRightOffset * 2),
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We shouldn't need to Math.ceil if we are not scaling now.

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I think the original reason that we did scaling is because we did not encode a pasp atom with sarRatio information when mux.js was created. So We had to encode width and height as their real values at all times. I think we should have been scaling height in some scenarios too. Overall we won't have to do any of that now as the decoder will see the pasp and scale accordingly. We just have to report the values that exist.

height: ((2 - frameMbsOnlyFlag) * (picHeightInMapUnitsMinus1 + 1) * 16) - (frameCropTopOffset * 2) - (frameCropBottomOffset * 2),
// sar is sample aspect ratio
sarRatio: sarRatio
};
};
Expand Down
10 changes: 5 additions & 5 deletions test/transmuxer.test.js
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Expand Up @@ -853,7 +853,7 @@ QUnit.test('properly parses seq_parameter_set_rbsp nal units', function(assert)
profileCompatibility: 192,
width: 720,
height: 404,
sarRatio: undefined
sarRatio: [1, 1]
};

h264Stream.on('data', function(event) {
Expand Down Expand Up @@ -889,7 +889,7 @@ QUnit.test('Properly parses seq_parameter_set VUI nal unit', function(assert) {
profileIdc: 66,
levelIdc: 30,
profileCompatibility: 192,
width: 64,
width: 16,
height: 16,
sarRatio: [65528, 16384]
};
Expand Down Expand Up @@ -924,7 +924,7 @@ QUnit.test('Properly parses seq_parameter_set nal unit with defined sarRatio', f
profileIdc: 77,
levelIdc: 21,
profileCompatibility: 64,
width: 640,
width: 352,
height: 480,
sarRatio: [20, 11]
};
Expand Down Expand Up @@ -959,7 +959,7 @@ QUnit.test('Properly parses seq_parameter_set nal unit with extended sarRatio',
profileIdc: 77,
levelIdc: 21,
profileCompatibility: 64,
width: 403,
width: 352,
height: 480,
sarRatio: [8, 7]
};
Expand Down Expand Up @@ -994,7 +994,7 @@ QUnit.test('Properly parses seq_parameter_set nal unit without VUI', function(as
profileCompatibility: 64,
width: 352,
height: 480,
sarRatio: undefined
sarRatio: [1, 1]
};

h264Stream.on('data', function(event) {
Expand Down