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Write the MA1B brand correctly #2515

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Write the MA1B brand correctly #2515

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Write the MA1B brand correctly
wantehchang Dec 2, 2024
5fd0303
Run clang-format
wantehchang Dec 2, 2024
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13 changes: 10 additions & 3 deletions src/write.c
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Original file line number Diff line number Diff line change
Expand Up @@ -3134,6 +3134,7 @@ avifResult avifEncoderFinish(avifEncoder * encoder, avifRWData * output)
// -----------------------------------------------------------------------
// Harvest configuration properties from sequence headers

avifBool isMA1B = AVIF_TRUE;
for (uint32_t itemIndex = 0; itemIndex < encoder->data->items.count; ++itemIndex) {
avifEncoderItem * item = &encoder->data->items.item[itemIndex];
if (item->encodeOutput->samples.count > 0) {
Expand All @@ -3142,6 +3143,11 @@ avifResult avifEncoderFinish(avifEncoder * encoder, avifRWData * output)
AVIF_CHECKERR(avifSequenceHeaderParse(&sequenceHeader, (const avifROData *)&firstSample->data, codecType),
avifGetErrorForItemCategory(item->itemCategory));
item->av1C = sequenceHeader.av1C;
// The MA1B brand: The AV1 profile shall be the Main Profile and the level shall be 5.1
// or lower.
if (item->av1C.seqProfile != 0 || item->av1C.seqLevelIdx0 > 13) {
isMA1B = AVIF_FALSE;
}
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@wantehchang wantehchang Dec 3, 2024

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Yannis: I am not that familiar with this code. It is important that this for loop (which starts at line 3138) is executed for both image items and image sequences, and that we enter the if (item->encodeOutput->samples.count > 0) block (which starts at line 3140) at least once. Otherwise we will incorrectly report that isMA1B is true (the initial value). Please check this. Thanks!

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@y-guyon y-guyon Dec 3, 2024

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Here is my understanding:

  • A track exists in avifEncoder only if the corresponding item is present too, likely with the first frame of the sequence being used as the image item data.
  • There is no change of profile/level within a single sequence.

Assuming this is correct, the for loop and the MA1B check look good.

}
}

Expand Down Expand Up @@ -3239,10 +3245,11 @@ avifResult avifEncoderFinish(avifEncoder * encoder, avifRWData * output)
} //
AVIF_CHECKRES(avifRWStreamWriteChars(&s, "mif1", 4)); // ... compatible_brands[]
AVIF_CHECKRES(avifRWStreamWriteChars(&s, "miaf", 4)); // ... compatible_brands[]
if (isMA1B) { //
AVIF_CHECKRES(avifRWStreamWriteChars(&s, "MA1B", 4)); // ... compatible_brands[]
} //
if ((imageMetadata->depth == 8) || (imageMetadata->depth == 10)) { //
if (imageMetadata->yuvFormat == AVIF_PIXEL_FORMAT_YUV420) { //
AVIF_CHECKRES(avifRWStreamWriteChars(&s, "MA1B", 4)); // ... compatible_brands[]
} else if (imageMetadata->yuvFormat == AVIF_PIXEL_FORMAT_YUV444) { //
if (imageMetadata->yuvFormat == AVIF_PIXEL_FORMAT_YUV444) { //
AVIF_CHECKRES(avifRWStreamWriteChars(&s, "MA1A", 4)); // ... compatible_brands[]
}
}
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