Traneptora/FFmpeg
1
Fork 0
forked from FFmpeg/FFmpeg
Code Pull requests Activity

ffv1dec: move slice start finding into a function

Browse source 
This also cleans up and gives the code some much needed comments.
This commit is contained in:
Lynne 2025-01-05 13:51:52 +09:00
parent 7187eadf8c
commit d987feae2a
Signed by: Lynne
GPG key ID: A2FEA5F03F034464
1 changed files with 47 additions and 19 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

66
libavcodec/ffv1dec.c
View file

@ -869,6 +869,38 @@ static av_cold int decode_init(AVCodecContext *avctx)
return 0; return 0;
} }
static int find_next_slice(AVCodecContext *avctx,
uint8_t *buf, uint8_t *buf_end, int idx,
uint8_t **pos, uint32_t *len)
{
FFV1Context *f = avctx->priv_data;
/* Length field */
uint32_t v = buf_end - buf;
if (idx || f->version > 2) {
/* Three bytes of length, plus flush bit + CRC */
uint32_t trailer = 3 + 5*!!f->ec;
if (trailer > buf_end - buf)
v = INT_MAX;
else
v = AV_RB24(buf_end - trailer) + trailer;
}
if (buf_end - buf < v) {
av_log(avctx, AV_LOG_ERROR, "Slice pointer chain broken\n");
ff_progress_frame_report(&f->picture, INT_MAX);
return AVERROR_INVALIDDATA;
}
*len = v;
if (idx)
*pos = buf_end - v;
else
*pos = buf;
return 0;
}
static int decode_frame(AVCodecContext *avctx, AVFrame *rframe, static int decode_frame(AVCodecContext *avctx, AVFrame *rframe,
int *got_frame, AVPacket *avpkt) int *got_frame, AVPacket *avpkt)
{ {
@ -878,7 +910,7 @@ static int decode_frame(AVCodecContext *avctx, AVFrame *rframe,
RangeCoder *const c = &f->slices[0].c; RangeCoder *const c = &f->slices[0].c;
int ret, key_frame; int ret, key_frame;
uint8_t keystate = 128; uint8_t keystate = 128;
uint8_t *buf_p; uint8_t *buf_end;
AVFrame *p; AVFrame *p;
ff_progress_frame_unref(&f->last_picture); ff_progress_frame_unref(&f->last_picture);
@ -944,27 +976,23 @@ static int decode_frame(AVCodecContext *avctx, AVFrame *rframe,
ff_thread_finish_setup(avctx); ff_thread_finish_setup(avctx);
buf_p = buf + buf_size; buf_end = buf + buf_size;
for (int i = f->slice_count - 1; i >= 0; i--) { for (int i = f->slice_count - 1; i >= 0; i--) {
FFV1SliceContext *sc = &f->slices[i]; FFV1SliceContext *sc = &f->slices[i];
int trailer = 3 + 5*!!f->ec;
int v; uint8_t *pos;
uint32_t len;
int err = find_next_slice(avctx, buf, buf_end, i,
&pos, &len);
if (err < 0)
return err;
buf_end -= len;
sc->slice_damaged = 0; sc->slice_damaged = 0;
if (i || f->version > 2) {
if (trailer > buf_p - buf) v = INT_MAX;
else v = AV_RB24(buf_p-trailer) + trailer;
} else v = buf_p - c->bytestream_start;
if (buf_p - c->bytestream_start < v) {
av_log(avctx, AV_LOG_ERROR, "Slice pointer chain broken\n");
ff_progress_frame_report(&f->picture, INT_MAX);
return AVERROR_INVALIDDATA;
}
buf_p -= v;
if (f->ec) { if (f->ec) {
unsigned crc = av_crc(av_crc_get_table(AV_CRC_32_IEEE), f->crcref, buf_p, v); unsigned crc = av_crc(av_crc_get_table(AV_CRC_32_IEEE), f->crcref, pos, len);
if (crc != f->crcref) { if (crc != f->crcref) {
int64_t ts = avpkt->pts != AV_NOPTS_VALUE ? avpkt->pts : avpkt->dts; int64_t ts = avpkt->pts != AV_NOPTS_VALUE ? avpkt->pts : avpkt->dts;
av_log(f->avctx, AV_LOG_ERROR, "slice CRC mismatch %X!", crc); av_log(f->avctx, AV_LOG_ERROR, "slice CRC mismatch %X!", crc);
@ -978,15 +1006,15 @@ static int decode_frame(AVCodecContext *avctx, AVFrame *rframe,
slice_set_damaged(f, sc); slice_set_damaged(f, sc);
} }
if (avctx->debug & FF_DEBUG_PICT_INFO) { if (avctx->debug & FF_DEBUG_PICT_INFO) {
av_log(avctx, AV_LOG_DEBUG, "slice %d, CRC: 0x%08"PRIX32"\n", i, AV_RB32(buf_p + v - 4)); av_log(avctx, AV_LOG_DEBUG, "slice %d, CRC: 0x%08"PRIX32"\n", i, AV_RB32(pos + len - 4));
} }
} }
if (i) { if (i) {
ff_init_range_decoder(&sc->c, buf_p, v); ff_init_range_decoder(&sc->c, pos, len);
ff_build_rac_states(&sc->c, 0.05 * (1LL << 32), 256 - 8); ff_build_rac_states(&sc->c, 0.05 * (1LL << 32), 256 - 8);
} else } else
sc->c.bytestream_end = buf_p + v; sc->c.bytestream_end = pos + len;
} }