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[FFmpeg-devel,7/9] avcodec/vc2enc: Don't use bitcount when byte-aligned

Message ID GV1P250MB0737A05198CB562AD577607C8F5C9@GV1P250MB0737.EURP250.PROD.OUTLOOK.COM
State Accepted
Commit d2dc6440e6d46d34cfb7d925d4a5420cebf5bf66
Headers show
Series None | expand

Commit Message

Andreas Rheinhardt Oct. 6, 2022, 12:57 a.m. UTC 
(There is a small issue that is now being treated differently:
The earlier code would record a position in a buffer that
is being written to via put_bits(), then write data,
then overwrite the byte at the position recorded earlier
and only then flush the PutBitContext. In case there was
no writeout in the meantime, said flush would overwrite
what one has just written. This never happened in my tests,
but maybe it can happen. In this case this commit fixes
this issue by flushing before overwriting the old data.)

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
---
 libavcodec/vc2enc.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)
diff mbox series

Patch

diff --git a/libavcodec/vc2enc.c b/libavcodec/vc2enc.c
index 5cb6e0d198..82d11462aa 100644
--- a/libavcodec/vc2enc.c
+++ b/libavcodec/vc2enc.c
@@ -233,7 +233,7 @@  static void encode_parse_info(VC2EncContext *s, enum DiracParseCodes pcode)
 
     align_put_bits(&s->pb);
 
-    cur_pos = put_bits_count(&s->pb) >> 3;
+    cur_pos = put_bytes_count(&s->pb, 0);
 
     /* Magic string */
     ff_put_string(&s->pb, "BBCD", 0);
@@ -746,7 +746,7 @@  static int encode_hq_slice(AVCodecContext *avctx, void *arg)
     /* Luma + 2 Chroma planes */
     for (p = 0; p < 3; p++) {
         int bytes_start, bytes_len, pad_s, pad_c;
-        bytes_start = put_bits_count(pb) >> 3;
+        bytes_start = put_bytes_count(pb, 0);
         put_bits(pb, 8, 0);
         for (level = 0; level < s->wavelet_depth; level++) {
             for (orientation = !!level; orientation < 4; orientation++) {
@@ -755,10 +755,10 @@  static int encode_hq_slice(AVCodecContext *avctx, void *arg)
                                quants[level][orientation]);
             }
         }
-        align_put_bits(pb);
-        bytes_len = (put_bits_count(pb) >> 3) - bytes_start - 1;
+        flush_put_bits(pb);
+        bytes_len = put_bytes_output(pb) - bytes_start - 1;
         if (p == 2) {
-            int len_diff = slice_bytes_max - (put_bits_count(pb) >> 3);
+            int len_diff = slice_bytes_max - put_bytes_output(pb);
             pad_s = FFALIGN((bytes_len + len_diff), s->size_scaler)/s->size_scaler;
             pad_c = (pad_s*s->size_scaler) - bytes_len;
         } else {
@@ -766,7 +766,6 @@  static int encode_hq_slice(AVCodecContext *avctx, void *arg)
             pad_c = (pad_s*s->size_scaler) - bytes_len;
         }
         pb->buf[bytes_start] = pad_s;
-        flush_put_bits(pb);
         /* vc2-reference uses that padding that decodes to '0' coeffs */
         memset(put_bits_ptr(pb), 0xFF, pad_c);
         skip_put_bytes(pb, pad_c);