PeerStreamer

/*

 * H.26L/H.264/AVC/JVT/14496-10/... parser

 * Copyright (c) 2003 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

 */

/**

 * @file libavcodec/h264_parser.c

 * H.264 / AVC / MPEG4 part10 parser.

 * @author Michael Niedermayer <michaelni@gmx.at>

 */

#include "parser.h"

#include "h264_parser.h"

#include "h264data.h"

#include "golomb.h"

#include <assert.h>

int ff_h264_find_frame_end(H264Context *h, const uint8_t *buf, int buf_size)

{

    int i;

    uint32_t state;

    ParseContext *pc = &(h->s.parse_context);

//printf("first %02X%02X%02X%02X\n", buf[0], buf[1],buf[2],buf[3]);

//    mb_addr= pc->mb_addr - 1;

    state= pc->state;

    if(state>13)

        state= 7;

    for(i=0; i<buf_size; i++){

        if(state==7){

#if HAVE_FAST_UNALIGNED

        /* we check i<buf_size instead of i+3/7 because its simpler

         * and there should be FF_INPUT_BUFFER_PADDING_SIZE bytes at the end

         */

#    if HAVE_FAST_64BIT

            while(i<buf_size && !((~*(const uint64_t*)(buf+i) & (*(const uint64_t*)(buf+i) - 0x0101010101010101ULL)) & 0x8080808080808080ULL))

                i+=8;

#    else

            while(i<buf_size && !((~*(const uint32_t*)(buf+i) & (*(const uint32_t*)(buf+i) - 0x01010101U)) & 0x80808080U))

                i+=4;

#    endif

#endif

            for(; i<buf_size; i++){

                if(!buf[i]){

                    state=2;

                    break;

                }

            }

        }else if(state<=2){

            if(buf[i]==1)   state^= 5; //2->7, 1->4, 0->5

            else if(buf[i]) state = 7;

            else            state>>=1; //2->1, 1->0, 0->0

        }else if(state<=5){

            int v= buf[i] & 0x1F;

            if(v==6 || v==7 || v==8 || v==9){

                if(pc->frame_start_found){

                    i++;

                    goto found;

                }

            }else if(v==1 || v==2 || v==5){

                if(pc->frame_start_found){

                    state+=8;

                    continue;

                }else

                    pc->frame_start_found = 1;

            }

            state= 7;

        }else{

            if(buf[i] & 0x80)

                goto found;

            state= 7;

        }

    }

    pc->state= state;

    return END_NOT_FOUND;

found:

    pc->state=7;

    pc->frame_start_found= 0;

    return i-(state&5);

}

/*!

 * Parse NAL units of found picture and decode some basic information.

 *

 * @param s parser context.

 * @param avctx codec context.

 * @param buf buffer with field/frame data.

 * @param buf_size size of the buffer.

 */

static inline int parse_nal_units(AVCodecParserContext *s,

                                  AVCodecContext *avctx,

                                  const uint8_t *buf, int buf_size)

{

    H264Context *h = s->priv_data;

    const uint8_t *buf_end = buf + buf_size;

    unsigned int pps_id;

    unsigned int slice_type;

    int state = -1;

    const uint8_t *ptr;

    /* set some sane default values */

    s->pict_type = FF_I_TYPE;

    s->key_frame = 0;

    h->s.avctx= avctx;

    h->sei_recovery_frame_cnt = -1;

    h->sei_dpb_output_delay         =  0;

    h->sei_cpb_removal_delay        = -1;

    h->sei_buffering_period_present =  0;

    for(;;) {

        int src_length, dst_length, consumed;

        buf = ff_find_start_code(buf, buf_end, &state);

        if(buf >= buf_end)

            break;

        --buf;

        src_length = buf_end - buf;

        switch (state & 0x1f) {

        case NAL_SLICE:

        case NAL_IDR_SLICE:

            // Do not walk the whole buffer just to decode slice header

            if (src_length > 20)

                src_length = 20;

            break;

        }

        ptr= ff_h264_decode_nal(h, buf, &dst_length, &consumed, src_length);

        if (ptr==NULL || dst_length < 0)

            break;

        init_get_bits(&h->s.gb, ptr, 8*dst_length);

        switch(h->nal_unit_type) {

        case NAL_SPS:

            ff_h264_decode_seq_parameter_set(h);

            break;

        case NAL_PPS:

            ff_h264_decode_picture_parameter_set(h, h->s.gb.size_in_bits);

            break;

        case NAL_SEI:

            ff_h264_decode_sei(h);

            break;

        case NAL_IDR_SLICE:

            s->key_frame = 1;

            /* fall through */

        case NAL_SLICE:

            get_ue_golomb(&h->s.gb);  // skip first_mb_in_slice

            slice_type = get_ue_golomb_31(&h->s.gb);

            s->pict_type = golomb_to_pict_type[slice_type % 5];

            if (h->sei_recovery_frame_cnt >= 0) {

                /* key frame, since recovery_frame_cnt is set */

                s->key_frame = 1;

            }

            pps_id= get_ue_golomb(&h->s.gb);

            if(pps_id>=MAX_PPS_COUNT) {

                av_log(h->s.avctx, AV_LOG_ERROR, "pps_id out of range\n");

                return -1;

            }

            if(!h->pps_buffers[pps_id]) {

                av_log(h->s.avctx, AV_LOG_ERROR, "non-existing PPS referenced\n");

                return -1;

            }

            h->pps= *h->pps_buffers[pps_id];

            if(!h->sps_buffers[h->pps.sps_id]) {

                av_log(h->s.avctx, AV_LOG_ERROR, "non-existing SPS referenced\n");

                return -1;

            }

            h->sps = *h->sps_buffers[h->pps.sps_id];

            h->frame_num = get_bits(&h->s.gb, h->sps.log2_max_frame_num);

            if(h->sps.frame_mbs_only_flag){

                h->s.picture_structure= PICT_FRAME;

            }else{

                if(get_bits1(&h->s.gb)) { //field_pic_flag

                    h->s.picture_structure= PICT_TOP_FIELD + get_bits1(&h->s.gb); //bottom_field_flag

                } else {

                    h->s.picture_structure= PICT_FRAME;

                }

            }

            if(h->sps.pic_struct_present_flag) {

                switch (h->sei_pic_struct) {

                    case SEI_PIC_STRUCT_TOP_FIELD:

                    case SEI_PIC_STRUCT_BOTTOM_FIELD:

                        s->repeat_pict = 0;

                        break;

                    case SEI_PIC_STRUCT_FRAME:

                    case SEI_PIC_STRUCT_TOP_BOTTOM:

                    case SEI_PIC_STRUCT_BOTTOM_TOP:

                        s->repeat_pict = 1;

                        break;

                    case SEI_PIC_STRUCT_TOP_BOTTOM_TOP:

                    case SEI_PIC_STRUCT_BOTTOM_TOP_BOTTOM:

                        s->repeat_pict = 2;

                        break;

                    case SEI_PIC_STRUCT_FRAME_DOUBLING:

                        s->repeat_pict = 3;

                        break;

                    case SEI_PIC_STRUCT_FRAME_TRIPLING:

                        s->repeat_pict = 5;

                        break;

                    default:

                        s->repeat_pict = h->s.picture_structure == PICT_FRAME ? 1 : 0;

                        break;

                }

            } else {

                s->repeat_pict = h->s.picture_structure == PICT_FRAME ? 1 : 0;

            }

            return 0; /* no need to evaluate the rest */

        }

        buf += consumed;

    }

    /* didn't find a picture! */

    av_log(h->s.avctx, AV_LOG_ERROR, "missing picture in access unit\n");

    return -1;

}

static int h264_parse(AVCodecParserContext *s,

                      AVCodecContext *avctx,

                      const uint8_t **poutbuf, int *poutbuf_size,

                      const uint8_t *buf, int buf_size)

{

    H264Context *h = s->priv_data;

    ParseContext *pc = &h->s.parse_context;

    int next;

    if(s->flags & PARSER_FLAG_COMPLETE_FRAMES){

        next= buf_size;

    }else{

        next= ff_h264_find_frame_end(h, buf, buf_size);

        if (ff_combine_frame(pc, next, &buf, &buf_size) < 0) {

            *poutbuf = NULL;

            *poutbuf_size = 0;

            return buf_size;

        }

        if(next<0 && next != END_NOT_FOUND){

            assert(pc->last_index + next >= 0 );

            ff_h264_find_frame_end(h, &pc->buffer[pc->last_index + next], -next); //update state

        }

        parse_nal_units(s, avctx, buf, buf_size);

        if (h->sei_cpb_removal_delay >= 0) {

            s->dts_sync_point    = h->sei_buffering_period_present;

            s->dts_ref_dts_delta = h->sei_cpb_removal_delay;

            s->pts_dts_delta     = h->sei_dpb_output_delay;

        } else {

            s->dts_sync_point    = INT_MIN;

            s->dts_ref_dts_delta = INT_MIN;

            s->pts_dts_delta     = INT_MIN;

        }

    }

    *poutbuf = buf;

    *poutbuf_size = buf_size;

    return next;

}

static int h264_split(AVCodecContext *avctx,

                      const uint8_t *buf, int buf_size)

{

    int i;

    uint32_t state = -1;

    int has_sps= 0;

    for(i=0; i<=buf_size; i++){

        if((state&0xFFFFFF1F) == 0x107)

            has_sps=1;

/*        if((state&0xFFFFFF1F) == 0x101 || (state&0xFFFFFF1F) == 0x102 || (state&0xFFFFFF1F) == 0x105){

        }*/

        if((state&0xFFFFFF00) == 0x100 && (state&0xFFFFFF1F) != 0x107 && (state&0xFFFFFF1F) != 0x108 && (state&0xFFFFFF1F) != 0x109){

            if(has_sps){

                while(i>4 && buf[i-5]==0) i--;

                return i-4;

            }

        }

        if (i<buf_size)

            state= (state<<8) | buf[i];

    }

    return 0;

}

static void close(AVCodecParserContext *s)

{

    H264Context *h = s->priv_data;

    ParseContext *pc = &h->s.parse_context;

    av_free(pc->buffer);

    ff_h264_free_context(h);

}

static int init(AVCodecParserContext *s)

{

    H264Context *h = s->priv_data;

    h->thread_context[0] = h;

    return 0;

}

AVCodecParser h264_parser = {

    { CODEC_ID_H264 },

    sizeof(H264Context),

    init,

    h264_parse,

    close,

    h264_split,

};