nutenc.c

mediastreamer2是开源的网络传输媒体流的库

/*
 * nut muxer
 * Copyright (c) 2004-2007 Michael Niedermayer
 *
 * 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 "nut.h"
#include "tree.h"

static void build_frame_code(AVFormatContext *s){
    NUTContext *nut = s->priv_data;
    int key_frame, index, pred, stream_id;
    int start=1;
    int end= 254;
    int keyframe_0_esc= s->nb_streams > 2;
    int pred_table[10];
    FrameCode *ft;

    ft= &nut->frame_code[start];
    ft->flags= FLAG_CODED;
    ft->size_mul=1;
    ft->pts_delta=1;
    start++;

    if(keyframe_0_esc){
        /* keyframe = 0 escape */
        FrameCode *ft= &nut->frame_code[start];
        ft->flags= FLAG_STREAM_ID | FLAG_SIZE_MSB | FLAG_CODED_PTS;
        ft->size_mul=1;
        start++;
    }

    for(stream_id= 0; stream_id<s->nb_streams; stream_id++){
        int start2= start + (end-start)*stream_id / s->nb_streams;
        int end2  = start + (end-start)*(stream_id+1) / s->nb_streams;
        AVCodecContext *codec = s->streams[stream_id]->codec;
        int is_audio= codec->codec_type == CODEC_TYPE_AUDIO;
        int intra_only= /*codec->intra_only || */is_audio;
        int pred_count;

        for(key_frame=0; key_frame<2; key_frame++){
            if(intra_only && keyframe_0_esc && key_frame==0)
                continue;

            {
                FrameCode *ft= &nut->frame_code[start2];
                ft->flags= FLAG_KEY*key_frame;
                ft->flags|= FLAG_SIZE_MSB | FLAG_CODED_PTS;
                ft->stream_id= stream_id;
                ft->size_mul=1;
                start2++;
            }
        }

        key_frame= intra_only;
#if 1
        if(is_audio){
            int frame_bytes= codec->frame_size*(int64_t)codec->bit_rate / (8*codec->sample_rate);
            int pts;
            for(pts=0; pts<2; pts++){
                for(pred=0; pred<2; pred++){
                    FrameCode *ft= &nut->frame_code[start2];
                    ft->flags= FLAG_KEY*key_frame;
                    ft->stream_id= stream_id;
                    ft->size_mul=frame_bytes + 2;
                    ft->size_lsb=frame_bytes + pred;
                    ft->pts_delta=pts;
                    start2++;
                }
            }
        }else{
            FrameCode *ft= &nut->frame_code[start2];
            ft->flags= FLAG_KEY | FLAG_SIZE_MSB;
            ft->stream_id= stream_id;
            ft->size_mul=1;
            ft->pts_delta=1;
            start2++;
        }
#endif

        if(codec->has_b_frames){
            pred_count=5;
            pred_table[0]=-2;
            pred_table[1]=-1;
            pred_table[2]=1;
            pred_table[3]=3;
            pred_table[4]=4;
        }else if(codec->codec_id == CODEC_ID_VORBIS){
            pred_count=3;
            pred_table[0]=2;
            pred_table[1]=9;
            pred_table[2]=16;
        }else{
            pred_count=1;
            pred_table[0]=1;
        }

        for(pred=0; pred<pred_count; pred++){
            int start3= start2 + (end2-start2)*pred / pred_count;
            int end3  = start2 + (end2-start2)*(pred+1) / pred_count;

            for(index=start3; index<end3; index++){
                FrameCode *ft= &nut->frame_code[index];
                ft->flags= FLAG_KEY*key_frame;
                ft->flags|= FLAG_SIZE_MSB;
                ft->stream_id= stream_id;
//FIXME use single byte size and pred from last
                ft->size_mul= end3-start3;
                ft->size_lsb= index - start3;
                ft->pts_delta= pred_table[pred];
            }
        }
    }
    memmove(&nut->frame_code['N'+1], &nut->frame_code['N'], sizeof(FrameCode)*(255-'N'));
    nut->frame_code[  0].flags=
    nut->frame_code[255].flags=
    nut->frame_code['N'].flags= FLAG_INVALID;
}

/**
 * Gets the length in bytes which is needed to store val as v.
 */
static int get_length(uint64_t val){
    int i=1;

    while(val>>=7)
        i++;

    return i;
}

static void put_v(ByteIOContext *bc, uint64_t val){
    int i= get_length(val);

    while(--i>0)
        put_byte(bc, 128 | (val>>(7*i)));

    put_byte(bc, val&127);
}

static void put_t(NUTContext *nut, StreamContext *nus, ByteIOContext *bc, uint64_t val){
    val *= nut->time_base_count;
    val += nus->time_base - nut->time_base;
    put_v(bc, val);
}

/**
 * Stores a string as vb.
 */
static void put_str(ByteIOContext *bc, const char *string){
    int len= strlen(string);

    put_v(bc, len);
    put_buffer(bc, string, len);
}

static void put_s(ByteIOContext *bc, int64_t val){
    put_v(bc, 2*FFABS(val) - (val>0));
}

#ifdef TRACE
static inline void put_v_trace(ByteIOContext *bc, uint64_t v, char *file, char *func, int line){
    av_log(NULL, AV_LOG_DEBUG, "put_v %5"PRId64" / %"PRIX64" in %s %s:%d\n", v, v, file, func, line);

    put_v(bc, v);
}

static inline void put_s_trace(ByteIOContext *bc, int64_t v, char *file, char *func, int line){
    av_log(NULL, AV_LOG_DEBUG, "put_s %5"PRId64" / %"PRIX64" in %s %s:%d\n", v, v, file, func, line);

    put_s(bc, v);
}
#define put_v(bc, v)  put_v_trace(bc, v, __FILE__, __PRETTY_FUNCTION__, __LINE__)
#define put_s(bc, v)  put_s_trace(bc, v, __FILE__, __PRETTY_FUNCTION__, __LINE__)
#endif

//FIXME remove calculate_checksum
static void put_packet(NUTContext *nut, ByteIOContext *bc, ByteIOContext *dyn_bc, int calculate_checksum, uint64_t startcode){
    uint8_t *dyn_buf=NULL;
    int dyn_size= url_close_dyn_buf(dyn_bc, &dyn_buf);
    int forw_ptr= dyn_size + 4*calculate_checksum;

    if(forw_ptr > 4096)
        init_checksum(bc, ff_crc04C11DB7_update, 0);
    put_be64(bc, startcode);
    put_v(bc, forw_ptr);
    if(forw_ptr > 4096)
        put_le32(bc, get_checksum(bc));

    if(calculate_checksum)
        init_checksum(bc, ff_crc04C11DB7_update, 0);
    put_buffer(bc, dyn_buf, dyn_size);
    if(calculate_checksum)
        put_le32(bc, get_checksum(bc));

    av_free(dyn_buf);
}

static void write_mainheader(NUTContext *nut, ByteIOContext *bc){
    int i, j, tmp_pts, tmp_flags, tmp_stream, tmp_mul, tmp_size, tmp_fields;

    put_v(bc, 3); /* version */
    put_v(bc, nut->avf->nb_streams);
    put_v(bc, nut->max_distance);
    put_v(bc, nut->time_base_count);

    for(i=0; i<nut->time_base_count; i++){
        put_v(bc, nut->time_base[i].num);
        put_v(bc, nut->time_base[i].den);
    }

    tmp_pts=0;
    tmp_mul=1;
    tmp_stream=0;
    for(i=0; i<256;){
        tmp_fields=0;
        tmp_size=0;
//        tmp_res=0;
        if(tmp_pts    != nut->frame_code[i].pts_delta) tmp_fields=1;
        if(tmp_mul    != nut->frame_code[i].size_mul ) tmp_fields=2;
        if(tmp_stream != nut->frame_code[i].stream_id) tmp_fields=3;
        if(tmp_size   != nut->frame_code[i].size_lsb ) tmp_fields=4;
//        if(tmp_res    != nut->frame_code[i].res            ) tmp_fields=5;

        tmp_pts   = nut->frame_code[i].pts_delta;
        tmp_flags = nut->frame_code[i].flags;
        tmp_stream= nut->frame_code[i].stream_id;
        tmp_mul   = nut->frame_code[i].size_mul;
        tmp_size  = nut->frame_code[i].size_lsb;
//        tmp_res   = nut->frame_code[i].res;

        for(j=0; i<256; j++,i++){
            if(i == 'N'){
                j--;
                continue;
            }
            if(nut->frame_code[i].pts_delta != tmp_pts   ) break;
            if(nut->frame_code[i].flags     != tmp_flags ) break;
            if(nut->frame_code[i].stream_id != tmp_stream) break;
            if(nut->frame_code[i].size_mul  != tmp_mul   ) break;
            if(nut->frame_code[i].size_lsb  != tmp_size+j) break;
//            if(nut->frame_code[i].res       != tmp_res   ) break;
        }
        if(j != tmp_mul - tmp_size) tmp_fields=6;

        put_v(bc, tmp_flags);
        put_v(bc, tmp_fields);
        if(tmp_fields>0) put_s(bc, tmp_pts);
        if(tmp_fields>1) put_v(bc, tmp_mul);
        if(tmp_fields>2) put_v(bc, tmp_stream);
        if(tmp_fields>3) put_v(bc, tmp_size);
        if(tmp_fields>4) put_v(bc, 0 /*tmp_res*/);
        if(tmp_fields>5) put_v(bc, j);
    }
}

static int write_streamheader(NUTContext *nut, ByteIOContext *bc, AVCodecContext *codec, int i){
    put_v(bc, i);
    switch(codec->codec_type){
    case CODEC_TYPE_VIDEO: put_v(bc, 0); break;
    case CODEC_TYPE_AUDIO: put_v(bc, 1); break;
//    case CODEC_TYPE_TEXT : put_v(bc, 2); break;
    default              : put_v(bc, 3); break;
    }
    put_v(bc, 4);
    if (codec->codec_tag){
        put_le32(bc, codec->codec_tag);
    }else
        return -1;

    put_v(bc, nut->stream[i].time_base - nut->time_base);
    put_v(bc, nut->stream[i].msb_pts_shift);
    put_v(bc, nut->stream[i].max_pts_distance);
    put_v(bc, codec->has_b_frames);
    put_byte(bc, 0); /* flags: 0x1 - fixed_fps, 0x2 - index_present */

    put_v(bc, codec->extradata_size);
    put_buffer(bc, codec->extradata, codec->extradata_size);

    switch(codec->codec_type){
    case CODEC_TYPE_AUDIO:
        put_v(bc, codec->sample_rate);
        put_v(bc, 1);
        put_v(bc, codec->channels);
        break;
    case CODEC_TYPE_VIDEO:
        put_v(bc, codec->width);
        put_v(bc, codec->height);

        if(codec->sample_aspect_ratio.num<=0 || codec->sample_aspect_ratio.den<=0){
            put_v(bc, 0);
            put_v(bc, 0);
        }else{