From d2dc6440e6d46d34cfb7d925d4a5420cebf5bf66 Mon Sep 17 00:00:00 2001 From: Andreas Rheinhardt Date: Thu, 6 Oct 2022 02:31:21 +0200 Subject: [PATCH] avcodec/vc2enc: Don't use bitcount when byte-aligned (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 --- libavcodec/vc2enc.c | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-) 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);