Re-order the boxes within "stbl"
The ISO-BMFF spec has a "recommendation" for how the boxes within
the "stbl" box should be ordered.
Text from Section 6.2.3 of the spec:
It is *recommended* that the boxes within the Sample Table Box be in the
following order: Sample Description, Time to Sample, Sample to Chunk,
Sample Size, Chunk Offset.
Change the writer code to update the order of these boxes to match
what is recommended in the spec.
Old order: stco, stsc, stsz, stss, stts, stsd.
New order: stsd, stts, stsc, stsz, stco, stss.
This also matches the box ordering used by other tools like ffmpeg.
Motivation behind this change:
The MP4 reader in the Android platform fails if this ordering is not
followed. While that is not the right behavior (since the spec does not
mandate the order, it is simply a "recommendation"), there is no harm
in fixing libavif to produce AVIF animations that are consumable on
Android.
Verification:
* Compliance warden has no issues with the new ordering.
* Files are playing back on Chrome like before.
diff --git a/src/write.c b/src/write.c
index bead4cc..fa981ba 100644
--- a/src/write.c
+++ b/src/write.c
@@ -1674,64 +1674,13 @@
avifRWStreamFinishBox(&s, dref);
avifRWStreamFinishBox(&s, dinf);
+ // The boxes within the "stbl" box are ordered using the following recommendation in ISO/IEC 14496-12, Section 6.2.3:
+ // 4) It is recommended that the boxes within the Sample Table Box be in the following order: Sample Description
+ // (stsd), Time to Sample (stts), Sample to Chunk (stsc), Sample Size (stsz), Chunk Offset (stco).
+ //
+ // Any boxes not listed in the above line are placed in the end (after the "stco" box).
avifBoxMarker stbl = avifRWStreamWriteBox(&s, "stbl", AVIF_BOX_SIZE_TBD);
- avifBoxMarker stco = avifRWStreamWriteFullBox(&s, "stco", AVIF_BOX_SIZE_TBD, 0, 0);
- avifRWStreamWriteU32(&s, 1); // unsigned int(32) entry_count;
- avifEncoderItemAddMdatFixup(item, &s); //
- avifRWStreamWriteU32(&s, 1); // unsigned int(32) chunk_offset; (set later)
- avifRWStreamFinishBox(&s, stco);
-
- avifBoxMarker stsc = avifRWStreamWriteFullBox(&s, "stsc", AVIF_BOX_SIZE_TBD, 0, 0);
- avifRWStreamWriteU32(&s, 1); // unsigned int(32) entry_count;
- avifRWStreamWriteU32(&s, 1); // unsigned int(32) first_chunk;
- avifRWStreamWriteU32(&s, item->encodeOutput->samples.count); // unsigned int(32) samples_per_chunk;
- avifRWStreamWriteU32(&s, 1); // unsigned int(32) sample_description_index;
- avifRWStreamFinishBox(&s, stsc);
-
- avifBoxMarker stsz = avifRWStreamWriteFullBox(&s, "stsz", AVIF_BOX_SIZE_TBD, 0, 0);
- avifRWStreamWriteU32(&s, 0); // unsigned int(32) sample_size;
- avifRWStreamWriteU32(&s, item->encodeOutput->samples.count); // unsigned int(32) sample_count;
- for (uint32_t sampleIndex = 0; sampleIndex < item->encodeOutput->samples.count; ++sampleIndex) {
- avifEncodeSample * sample = &item->encodeOutput->samples.sample[sampleIndex];
- avifRWStreamWriteU32(&s, (uint32_t)sample->data.size); // unsigned int(32) entry_size;
- }
- avifRWStreamFinishBox(&s, stsz);
-
- avifBoxMarker stss = avifRWStreamWriteFullBox(&s, "stss", AVIF_BOX_SIZE_TBD, 0, 0);
- avifRWStreamWriteU32(&s, syncSamplesCount); // unsigned int(32) entry_count;
- for (uint32_t sampleIndex = 0; sampleIndex < item->encodeOutput->samples.count; ++sampleIndex) {
- avifEncodeSample * sample = &item->encodeOutput->samples.sample[sampleIndex];
- if (sample->sync) {
- avifRWStreamWriteU32(&s, sampleIndex + 1); // unsigned int(32) sample_number;
- }
- }
- avifRWStreamFinishBox(&s, stss);
-
- avifBoxMarker stts = avifRWStreamWriteFullBox(&s, "stts", AVIF_BOX_SIZE_TBD, 0, 0);
- size_t sttsEntryCountOffset = avifRWStreamOffset(&s);
- uint32_t sttsEntryCount = 0;
- avifRWStreamWriteU32(&s, 0); // unsigned int(32) entry_count;
- for (uint32_t sampleCount = 0, frameIndex = 0; frameIndex < encoder->data->frames.count; ++frameIndex) {
- avifEncoderFrame * frame = &encoder->data->frames.frame[frameIndex];
- ++sampleCount;
- if (frameIndex < (encoder->data->frames.count - 1)) {
- avifEncoderFrame * nextFrame = &encoder->data->frames.frame[frameIndex + 1];
- if (frame->durationInTimescales == nextFrame->durationInTimescales) {
- continue;
- }
- }
- avifRWStreamWriteU32(&s, sampleCount); // unsigned int(32) sample_count;
- avifRWStreamWriteU32(&s, (uint32_t)frame->durationInTimescales); // unsigned int(32) sample_delta;
- sampleCount = 0;
- ++sttsEntryCount;
- }
- size_t prevOffset = avifRWStreamOffset(&s);
- avifRWStreamSetOffset(&s, sttsEntryCountOffset);
- avifRWStreamWriteU32(&s, sttsEntryCount);
- avifRWStreamSetOffset(&s, prevOffset);
- avifRWStreamFinishBox(&s, stts);
-
avifBoxMarker stsd = avifRWStreamWriteFullBox(&s, "stsd", AVIF_BOX_SIZE_TBD, 0, 0);
avifRWStreamWriteU32(&s, 1); // unsigned int(32) entry_count;
avifBoxMarker av01 = avifRWStreamWriteBox(&s, "av01", AVIF_BOX_SIZE_TBD);
@@ -1772,6 +1721,62 @@
avifRWStreamFinishBox(&s, av01);
avifRWStreamFinishBox(&s, stsd);
+ avifBoxMarker stts = avifRWStreamWriteFullBox(&s, "stts", AVIF_BOX_SIZE_TBD, 0, 0);
+ size_t sttsEntryCountOffset = avifRWStreamOffset(&s);
+ uint32_t sttsEntryCount = 0;
+ avifRWStreamWriteU32(&s, 0); // unsigned int(32) entry_count;
+ for (uint32_t sampleCount = 0, frameIndex = 0; frameIndex < encoder->data->frames.count; ++frameIndex) {
+ avifEncoderFrame * frame = &encoder->data->frames.frame[frameIndex];
+ ++sampleCount;
+ if (frameIndex < (encoder->data->frames.count - 1)) {
+ avifEncoderFrame * nextFrame = &encoder->data->frames.frame[frameIndex + 1];
+ if (frame->durationInTimescales == nextFrame->durationInTimescales) {
+ continue;
+ }
+ }
+ avifRWStreamWriteU32(&s, sampleCount); // unsigned int(32) sample_count;
+ avifRWStreamWriteU32(&s, (uint32_t)frame->durationInTimescales); // unsigned int(32) sample_delta;
+ sampleCount = 0;
+ ++sttsEntryCount;
+ }
+ size_t prevOffset = avifRWStreamOffset(&s);
+ avifRWStreamSetOffset(&s, sttsEntryCountOffset);
+ avifRWStreamWriteU32(&s, sttsEntryCount);
+ avifRWStreamSetOffset(&s, prevOffset);
+ avifRWStreamFinishBox(&s, stts);
+
+ avifBoxMarker stsc = avifRWStreamWriteFullBox(&s, "stsc", AVIF_BOX_SIZE_TBD, 0, 0);
+ avifRWStreamWriteU32(&s, 1); // unsigned int(32) entry_count;
+ avifRWStreamWriteU32(&s, 1); // unsigned int(32) first_chunk;
+ avifRWStreamWriteU32(&s, item->encodeOutput->samples.count); // unsigned int(32) samples_per_chunk;
+ avifRWStreamWriteU32(&s, 1); // unsigned int(32) sample_description_index;
+ avifRWStreamFinishBox(&s, stsc);
+
+ avifBoxMarker stsz = avifRWStreamWriteFullBox(&s, "stsz", AVIF_BOX_SIZE_TBD, 0, 0);
+ avifRWStreamWriteU32(&s, 0); // unsigned int(32) sample_size;
+ avifRWStreamWriteU32(&s, item->encodeOutput->samples.count); // unsigned int(32) sample_count;
+ for (uint32_t sampleIndex = 0; sampleIndex < item->encodeOutput->samples.count; ++sampleIndex) {
+ avifEncodeSample * sample = &item->encodeOutput->samples.sample[sampleIndex];
+ avifRWStreamWriteU32(&s, (uint32_t)sample->data.size); // unsigned int(32) entry_size;
+ }
+ avifRWStreamFinishBox(&s, stsz);
+
+ avifBoxMarker stco = avifRWStreamWriteFullBox(&s, "stco", AVIF_BOX_SIZE_TBD, 0, 0);
+ avifRWStreamWriteU32(&s, 1); // unsigned int(32) entry_count;
+ avifEncoderItemAddMdatFixup(item, &s); //
+ avifRWStreamWriteU32(&s, 1); // unsigned int(32) chunk_offset; (set later)
+ avifRWStreamFinishBox(&s, stco);
+
+ avifBoxMarker stss = avifRWStreamWriteFullBox(&s, "stss", AVIF_BOX_SIZE_TBD, 0, 0);
+ avifRWStreamWriteU32(&s, syncSamplesCount); // unsigned int(32) entry_count;
+ for (uint32_t sampleIndex = 0; sampleIndex < item->encodeOutput->samples.count; ++sampleIndex) {
+ avifEncodeSample * sample = &item->encodeOutput->samples.sample[sampleIndex];
+ if (sample->sync) {
+ avifRWStreamWriteU32(&s, sampleIndex + 1); // unsigned int(32) sample_number;
+ }
+ }
+ avifRWStreamFinishBox(&s, stss);
+
avifRWStreamFinishBox(&s, stbl);
avifRWStreamFinishBox(&s, minf);
