/libavformat/h264dec.c
http://github.com/FFmpeg/FFmpeg · C · 120 lines · 88 code · 12 blank · 20 comment · 33 complexity · 8a9388625ffe2c0e0ca36fc39f6a0463 MD5 · raw file
- /*
- * RAW H.264 video demuxer
- * Copyright (c) 2008 Michael Niedermayer <michaelni@gmx.at>
- *
- * This file is part of FFmpeg.
- *
- * FFmpeg is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Lesser General Public
- * License as published by the Free Software Foundation; either
- * version 2.1 of the License, or (at your option) any later version.
- *
- * FFmpeg is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- * Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public
- * License along with FFmpeg; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
- */
- #include "libavcodec/get_bits.h"
- #include "libavcodec/golomb.h"
- #include "avformat.h"
- #include "rawdec.h"
- #include "libavcodec/internal.h"
- #define MAX_SPS_COUNT 32
- #define MAX_PPS_COUNT 256
- static int h264_probe(const AVProbeData *p)
- {
- uint32_t code = -1;
- int sps = 0, pps = 0, idr = 0, res = 0, sli = 0;
- int i, ret;
- int pps_ids[MAX_PPS_COUNT+1] = {0};
- int sps_ids[MAX_SPS_COUNT+1] = {0};
- unsigned pps_id, sps_id;
- GetBitContext gb;
- for (i = 0; i + 2 < p->buf_size; i++) {
- code = (code << 8) + p->buf[i];
- if ((code & 0xffffff00) == 0x100) {
- int ref_idc = (code >> 5) & 3;
- int type = code & 0x1F;
- static const int8_t ref_zero[] = {
- 2, 0, 0, 0, 0, -1, 1, -1,
- -1, 1, 1, 1, 1, -1, 2, 2,
- 2, 2, 2, 0, 2, 2, 2, 2,
- 2, 2, 2, 2, 2, 2, 2, 2
- };
- if (code & 0x80) // forbidden_bit
- return 0;
- if (ref_zero[type] == 1 && ref_idc)
- return 0;
- if (ref_zero[type] == -1 && !ref_idc)
- return 0;
- if (ref_zero[type] == 2) {
- if (!(code == 0x100 && !p->buf[i + 1] && !p->buf[i + 2]))
- res++;
- }
- ret = init_get_bits8(&gb, p->buf + i + 1, p->buf_size - i - 1);
- if (ret < 0)
- return 0;
- switch (type) {
- case 1:
- case 5:
- get_ue_golomb_long(&gb);
- if (get_ue_golomb_long(&gb) > 9U)
- return 0;
- pps_id = get_ue_golomb_long(&gb);
- if (pps_id > MAX_PPS_COUNT)
- return 0;
- if (!pps_ids[pps_id])
- break;
- if (type == 1)
- sli++;
- else
- idr++;
- break;
- case 7:
- skip_bits(&gb, 14);
- if (get_bits(&gb, 2))
- return 0;
- skip_bits(&gb, 8);
- sps_id = get_ue_golomb_long(&gb);
- if (sps_id > MAX_SPS_COUNT)
- return 0;
- sps_ids[sps_id] = 1;
- sps++;
- break;
- case 8:
- pps_id = get_ue_golomb_long(&gb);
- if (pps_id > MAX_PPS_COUNT)
- return 0;
- sps_id = get_ue_golomb_long(&gb);
- if (sps_id > MAX_SPS_COUNT)
- return 0;
- if (!sps_ids[sps_id])
- break;
- pps_ids[pps_id] = 1;
- pps++;
- break;
- }
- }
- }
- ff_tlog(NULL, "sps:%d pps:%d idr:%d sli:%d res:%d\n", sps, pps, idr, sli, res);
- if (sps && pps && (idr || sli > 3) && res < (sps + pps + idr))
- return AVPROBE_SCORE_EXTENSION + 1; // 1 more than .mpg
- return 0;
- }
- FF_DEF_RAWVIDEO_DEMUXER(h264, "raw H.264 video", h264_probe, "h26l,h264,264,avc", AV_CODEC_ID_H264)