static void mpegvideo_extract_headers(AVCodecParserContext *s, AVCodecContext *avctx, const uint8_t *buf, int buf_size) { ParseContext1 *pc = s->priv_data; const uint8_t *buf_end; uint32_t start_code; int frame_rate_index, ext_type, bytes_left; int frame_rate_ext_n, frame_rate_ext_d; int picture_structure, top_field_first, repeat_first_field, progressive_frame; int horiz_size_ext, vert_size_ext, bit_rate_ext; //FIXME replace the crap with get_bits() s->repeat_pict = 0; buf_end = buf + buf_size; while (buf < buf_end) { start_code= -1; buf= ff_find_start_code(buf, buf_end, &start_code); bytes_left = buf_end - buf; switch(start_code) { case PICTURE_START_CODE: ff_fetch_timestamp(s, buf-buf_start-4, 1); if (bytes_left >= 2) { s->pict_type = (buf[1] >> 3) & 7; } break; case SEQ_START_CODE: if (bytes_left >= 7) { pc->width = (buf[0] << 4) | (buf[1] >> 4); pc->height = ((buf[1] & 0x0f) << 8) | buf[2]; avcodec_set_dimensions(avctx, pc->width, pc->height); frame_rate_index = buf[3] & 0xf; pc->frame_rate.den = avctx->time_base.den = ff_frame_rate_tab[frame_rate_index].num; pc->frame_rate.num = avctx->time_base.num = ff_frame_rate_tab[frame_rate_index].den; avctx->bit_rate = ((buf[4]<<10) | (buf[5]<<2) | (buf[6]>>6))*400; avctx->codec_id = CODEC_ID_MPEG1VIDEO; avctx->sub_id = 1; } break; case EXT_START_CODE: if (bytes_left >= 1) { ext_type = (buf[0] >> 4); switch(ext_type) { case 0x1: /* sequence extension */ if (bytes_left >= 6) { horiz_size_ext = ((buf[1] & 1) << 1) | (buf[2] >> 7); vert_size_ext = (buf[2] >> 5) & 3; bit_rate_ext = ((buf[2] & 0x1F)<<7) | (buf[3]>>1); frame_rate_ext_n = (buf[5] >> 5) & 3; frame_rate_ext_d = (buf[5] & 0x1f); pc->progressive_sequence = buf[1] & (1 << 3); avctx->has_b_frames= !(buf[5] >> 7); pc->width |=(horiz_size_ext << 12); pc->height |=( vert_size_ext << 12); avctx->bit_rate += (bit_rate_ext << 18) * 400; avcodec_set_dimensions(avctx, pc->width, pc->height); avctx->time_base.den = pc->frame_rate.den * (frame_rate_ext_n + 1); avctx->time_base.num = pc->frame_rate.num * (frame_rate_ext_d + 1); avctx->codec_id = CODEC_ID_MPEG2VIDEO; avctx->sub_id = 2; /* forces MPEG2 */ } break; case 0x8: /* picture coding extension */ if (bytes_left >= 5) { picture_structure = buf[2]&3; top_field_first = buf[3] & (1 << 7); repeat_first_field = buf[3] & (1 << 1); progressive_frame = buf[4] & (1 << 7); /* check if we must repeat the frame */ if (repeat_first_field) { if (pc->progressive_sequence) { if (top_field_first) s->repeat_pict = 4; else s->repeat_pict = 2; } else if (progressive_frame) { s->repeat_pict = 1; } } } break; } } break; case -1: goto the_end; default: /* we stop parsing when we encounter a slice. It ensures that this function takes a negligible amount of time */ if (start_code >= SLICE_MIN_START_CODE && start_code <= SLICE_MAX_START_CODE) goto the_end; break; } } the_end: ; }