avcodec/cbs: Factor out common code for writing units

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>

1 files changed, 0 insertions, 4 deletions

diff --git a/libavcodec/cbs_mpeg2.h b/libavcodec/cbs_mpeg2.h
index 118e63d804..5bcafd09f0 100644
--- a/libavcodec/cbs_mpeg2.h
+++ b/libavcodec/cbs_mpeg2.h
@@ -225,10 +225,6 @@ typedef struct CodedBitstreamMPEG2Context {
     uint8_t scalable_mode;
     uint8_t progressive_sequence;
     uint8_t number_of_frame_centre_offsets;
-
-    // Write buffer.
-    uint8_t *write_buffer;
-    size_t write_buffer_size;
 } CodedBitstreamMPEG2Context;