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avcodec/cbs: Factor out common code for writing units

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All cbs-functions to write units share a common pattern:
1. They check whether they have a write buffer (that is used to store
the unit's data until the needed size becomes known after writing the
unit when a dedicated buffer will be allocated).
2. They use this buffer for a PutBitContext.
3. The (codec-specific) writing takes place through the PutBitContext.
4. The return value is checked. AVERROR(ENOSPC) here always indicates
that the buffer was too small and leads to a reallocation of said
buffer.
5. The final buffer will be allocated and the data copied.

This commit factors this common code out in a single function in cbs.c.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
(cherry picked from commit 7c92eaace2)
This commit is contained in:
Andreas Rheinhardt
2019-11-17 08:34:35 +01:00
committed by James Almer
parent cb3a59ca82
commit 1cf238d3bf
13 changed files with 94 additions and 322 deletions
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64
libavcodec/cbs_jpeg.c
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@@ -377,58 +377,13 @@ static int cbs_jpeg_write_segment(CodedBitstreamContext *ctx,
}
static int cbs_jpeg_write_unit(CodedBitstreamContext *ctx,
CodedBitstreamUnit *unit)
CodedBitstreamUnit *unit,
PutBitContext *pbc)
{
CodedBitstreamJPEGContext *priv = ctx->priv_data;
PutBitContext pbc;
int err;
if (!priv->write_buffer) {
// Initial write buffer size is 1MB.
priv->write_buffer_size = 1024 * 1024;
reallocate_and_try_again:
err = av_reallocp(&priv->write_buffer, priv->write_buffer_size);
if (err < 0) {
av_log(ctx->log_ctx, AV_LOG_ERROR, "Unable to allocate a "
"sufficiently large write buffer (last attempt "
"%"SIZE_SPECIFIER" bytes).\n", priv->write_buffer_size);
return err;
}
}
init_put_bits(&pbc, priv->write_buffer, priv->write_buffer_size);
if (unit->type == JPEG_MARKER_SOS)
err = cbs_jpeg_write_scan(ctx, unit, &pbc);
return cbs_jpeg_write_scan (ctx, unit, pbc);
else
err = cbs_jpeg_write_segment(ctx, unit, &pbc);
if (err == AVERROR(ENOSPC)) {
// Overflow.
priv->write_buffer_size *= 2;
goto reallocate_and_try_again;
}
if (err < 0) {
// Write failed for some other reason.
return err;
}
if (put_bits_count(&pbc) % 8)
unit->data_bit_padding = 8 - put_bits_count(&pbc) % 8;
else
unit->data_bit_padding = 0;
unit->data_size = (put_bits_count(&pbc) + 7) / 8;
flush_put_bits(&pbc);
err = ff_cbs_alloc_unit_data(ctx, unit, unit->data_size);
if (err < 0)
return err;
memcpy(unit->data, priv->write_buffer, unit->data_size);
return 0;
return cbs_jpeg_write_segment(ctx, unit, pbc);
}
static int cbs_jpeg_assemble_fragment(CodedBitstreamContext *ctx,
@@ -499,22 +454,11 @@ static int cbs_jpeg_assemble_fragment(CodedBitstreamContext *ctx,
return 0;
}
static void cbs_jpeg_close(CodedBitstreamContext *ctx)
{
CodedBitstreamJPEGContext *priv = ctx->priv_data;
av_freep(&priv->write_buffer);
}
const CodedBitstreamType ff_cbs_type_jpeg = {
.codec_id = AV_CODEC_ID_MJPEG,
.priv_data_size = sizeof(CodedBitstreamJPEGContext),
.split_fragment = &cbs_jpeg_split_fragment,
.read_unit = &cbs_jpeg_read_unit,
.write_unit = &cbs_jpeg_write_unit,
.assemble_fragment = &cbs_jpeg_assemble_fragment,
.close = &cbs_jpeg_close,
};