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avcodec/ffv1: Implement CRC with non zero initial and final value

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Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
This commit is contained in:
Michael Niedermayer 2024-09-25 09:46:17 +02:00
parent b7ff66a358
commit 7bb283aa7b
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GPG Key ID: B18E8928B3948D64
3 changed files with 16 additions and 7 deletions
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1
libavcodec/ffv1.h
View File

@ -119,6 +119,7 @@ typedef struct FFV1Context {
int64_t picture_number;
int key_frame;
ProgressFrame picture, last_picture;
uint32_t crcref;
const AVFrame *cur_enc_frame;
int plane_count;

10
libavcodec/ffv1dec.c
View File

@ -502,15 +502,17 @@ static int read_extra_header(FFV1Context *f)
if (f->version > 2) {
f->ec = get_symbol(&c, state, 0);
if (f->ec >= 2)
f->crcref = 0x7a8c4079;
if (f->micro_version > 2)
f->intra = get_symbol(&c, state, 0);
}
if (f->version > 2) {
unsigned v;
v = av_crc(av_crc_get_table(AV_CRC_32_IEEE), 0,
v = av_crc(av_crc_get_table(AV_CRC_32_IEEE), f->crcref,
f->avctx->extradata, f->avctx->extradata_size);
if (v || f->avctx->extradata_size < 4) {
if (v != f->crcref || f->avctx->extradata_size < 4) {
av_log(f->avctx, AV_LOG_ERROR, "CRC mismatch %X!\n", v);
return AVERROR_INVALIDDATA;
}
@ -948,8 +950,8 @@ static int decode_frame(AVCodecContext *avctx, AVFrame *rframe,
buf_p -= v;
if (f->ec) {
unsigned crc = av_crc(av_crc_get_table(AV_CRC_32_IEEE), 0, buf_p, v);
if (crc) {
unsigned crc = av_crc(av_crc_get_table(AV_CRC_32_IEEE), f->crcref, buf_p, v);
if (crc != f->crcref) {
int64_t ts = avpkt->pts != AV_NOPTS_VALUE ? avpkt->pts : avpkt->dts;
av_log(f->avctx, AV_LOG_ERROR, "slice CRC mismatch %X!", crc);
if (ts != AV_NOPTS_VALUE && avctx->pkt_timebase.num) {

12
libavcodec/ffv1enc.c
View File

@ -458,7 +458,7 @@ static int write_extradata(FFV1Context *f)
}
f->avctx->extradata_size = ff_rac_terminate(&c, 0);
v = av_crc(av_crc_get_table(AV_CRC_32_IEEE), 0, f->avctx->extradata, f->avctx->extradata_size);
v = av_crc(av_crc_get_table(AV_CRC_32_IEEE), f->crcref, f->avctx->extradata, f->avctx->extradata_size) ^ (f->crcref ? 0x8CD88196 : 0);
AV_WL32(f->avctx->extradata + f->avctx->extradata_size, v);
f->avctx->extradata_size += 4;
@ -549,7 +549,13 @@ static av_cold int encode_init(AVCodecContext *avctx)
}
if (s->ec < 0) {
s->ec = (s->version >= 3);
if (s->version >= 4) {
s->ec = 2;
s->crcref = 0x7a8c4079;
} else if (s->version >= 3) {
s->ec = 1;
} else
s->ec = 0;
}
// CRC requires version 3+
@ -1239,7 +1245,7 @@ static int encode_frame(AVCodecContext *avctx, AVPacket *pkt,
if (f->ec) {
unsigned v;
buf_p[bytes++] = 0;
v = av_crc(av_crc_get_table(AV_CRC_32_IEEE), 0, buf_p, bytes);
v = av_crc(av_crc_get_table(AV_CRC_32_IEEE), f->crcref, buf_p, bytes) ^ (f->crcref ? 0x8CD88196 : 0);
AV_WL32(buf_p + bytes, v);
bytes += 4;
}