diff options
Diffstat (limited to 'libavcodec/mpegvideo_parser.c')
| -rw-r--r-- | libavcodec/mpegvideo_parser.c | 70 |
1 files changed, 70 insertions, 0 deletions
diff --git a/libavcodec/mpegvideo_parser.c b/libavcodec/mpegvideo_parser.c index 7864224643..39b9f2e43a 100644 --- a/libavcodec/mpegvideo_parser.c +++ b/libavcodec/mpegvideo_parser.c @@ -31,6 +31,72 @@ struct MpvParseContext { int width, height; }; +#if !FF_API_FLAG_TRUNCATED +/** + * Find the end of the current frame in the bitstream. + * @return the position of the first byte of the next frame, or -1 + */ +static int mpeg1_find_frame_end(ParseContext *pc, const uint8_t *buf, + int buf_size, AVCodecParserContext *s) +{ + int i; + uint32_t state = pc->state; + + /* EOF considered as end of frame */ + if (buf_size == 0) + return 0; + +/* + 0 frame start -> 1/4 + 1 first_SEQEXT -> 0/2 + 2 first field start -> 3/0 + 3 second_SEQEXT -> 2/0 + 4 searching end +*/ + + for (i = 0; i < buf_size; i++) { + av_assert1(pc->frame_start_found >= 0 && pc->frame_start_found <= 4); + if (pc->frame_start_found & 1) { + if (state == EXT_START_CODE && (buf[i] & 0xF0) != 0x80) + pc->frame_start_found--; + else if (state == EXT_START_CODE + 2) { + if ((buf[i] & 3) == 3) + pc->frame_start_found = 0; + else + pc->frame_start_found = (pc->frame_start_found + 1) & 3; + } + state++; + } else { + i = avpriv_find_start_code(buf + i, buf + buf_size, &state) - buf - 1; + if (pc->frame_start_found == 0 && state >= SLICE_MIN_START_CODE && state <= SLICE_MAX_START_CODE) { + i++; + pc->frame_start_found = 4; + } + if (state == SEQ_END_CODE) { + pc->frame_start_found = 0; + pc->state = -1; + return i + 1; + } + if (pc->frame_start_found == 2 && state == SEQ_START_CODE) + pc->frame_start_found = 0; + if (pc->frame_start_found < 4 && state == EXT_START_CODE) + pc->frame_start_found++; + if (pc->frame_start_found == 4 && (state & 0xFFFFFF00) == 0x100) { + if (state < SLICE_MIN_START_CODE || state > SLICE_MAX_START_CODE) { + pc->frame_start_found = 0; + pc->state = -1; + return i - 3; + } + } + if (pc->frame_start_found == 0 && s && state == PICTURE_START_CODE) { + ff_fetch_timestamp(s, i - 3, 1, i > 3); + } + } + } + pc->state = state; + return END_NOT_FOUND; +} +#endif static void mpegvideo_extract_headers(AVCodecParserContext *s, AVCodecContext *avctx, @@ -192,7 +258,11 @@ static int mpegvideo_parse(AVCodecParserContext *s, if(s->flags & PARSER_FLAG_COMPLETE_FRAMES){ next= buf_size; }else{ +#if FF_API_FLAG_TRUNCATED next= ff_mpeg1_find_frame_end(pc, buf, buf_size, s); +#else + next = mpeg1_find_frame_end(pc, buf, buf_size, s); +#endif if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) { *poutbuf = NULL; |