nginx_rtmp_module 之 ngx_rtmp_mp4_module 的mp4源码分析

一：整体代码函数预览

static?ngx_int_t
ngx_rtmp_mp4_postconfiguration(ngx_conf_t?*cf)
{
????ngx_rtmp_play_main_conf_t??????*pmcf;
????ngx_rtmp_play_fmt_t???????????**pfmt,?*fmt;
????pmcf?=?ngx_rtmp_conf_get_module_main_conf(cf,?ngx_rtmp_play_module);
????pfmt?=?ngx_array_push(&pmcf->fmts);
????if?(pfmt?==?NULL)?{
????????return?NGX_ERROR;
????}
????fmt?=?ngx_pcalloc(cf->pool,?sizeof(ngx_rtmp_play_fmt_t));
????if?(fmt?==?NULL)?{
????????return?NGX_ERROR;
????}
????*pfmt?=?fmt;
????ngx_str_set(&fmt->name,?"mp4-format");
????ngx_str_set(&fmt->pfx,?"mp4:");
????ngx_str_set(&fmt->sfx,?".mp4");
????fmt->init??=?ngx_rtmp_mp4_init;  // 初始化
????fmt->done??=?ngx_rtmp_mp4_done;  // 完成
????fmt->seek??=?ngx_rtmp_mp4_seek;  // seek
????fmt->start?=?ngx_rtmp_mp4_start; // 开始
????fmt->stop??=?ngx_rtmp_mp4_stop;  // 结束
????fmt->send??=?ngx_rtmp_mp4_send;  // 发送数据
????return?NGX_OK;
}

二：数据结构定义

定义	标准定义	nginx 数据结构定义
stsc 【Sample To Chunk Box】		type 4 字节已经偏移过， box_size 4 字节已经偏移过 typedef?struct?{ ????uint32_t????????????????????????????first_chunk; ????uint32_t????????????????????????????samples_per_chunk; ????uint32_t????????????????????????????sample_descrption_index; }?ngx_rtmp_mp4_chunk_entry_t; typedef?struct?{ ????uint32_t????????????????????????????version_flags; ????uint32_t????????????????????????????entry_count; ????ngx_rtmp_mp4_chunk_entry_t??????????entries[0]; }?ngx_rtmp_mp4_chunks_t;
stts 【Decoding Time to Sample Box】		type 4 字节已经偏移过， box_size 4 字节已经偏移过 typedef?struct?{ ????uint32_t????????????????????????????sample_count; ????uint32_t????????????????????????????sample_delta; }?ngx_rtmp_mp4_time_entry_t; typedef?struct?{ ????uint32_t????????????????????????????version_flags; ????uint32_t????????????????????????????entry_count; ????ngx_rtmp_mp4_time_entry_t???????????entries[0]; }?ngx_rtmp_mp4_times_t;
ctts 【Composition Time to Sample Box】		type 4 字节已经偏移过， box_size 4 字节已经偏移过 typedef?struct?{ ????uint32_t????????????????????????????sample_count; ????uint32_t????????????????????????????sample_offset; }?ngx_rtmp_mp4_delay_entry_t; typedef?struct?{ ????uint32_t????????????????????????????version_flags; ????uint32_t????????????????????????????entry_count; ????ngx_rtmp_mp4_delay_entry_t??????????entries[0]; }?ngx_rtmp_mp4_delays_t;
stss 【Sync Sample Box】		type 4 字节已经偏移过， box_size 4 字节已经偏移过 typedef?struct?{ ????uint32_t????????????????????????????version_flags; ????uint32_t????????????????????????????entry_count; ????uint32_t????????????????????????????entries[0]; }?ngx_rtmp_mp4_keys_t;
stsz 【Sample Size Boxes】		type 4 字节已经偏移过， box_size 4 字节已经偏移过 typedef?struct?{ ????uint32_t????????????????????????????version_flags; 4 字节 ????uint32_t????????????????????????????sample_size; ????uint32_t????????????????????????????sample_count; ????uint32_t????????????????????????????entries[0]; }?ngx_rtmp_mp4_sizes_t;
stco 【Chunk Offset Box】 co64		type 4 字节已经偏移过， box_size 4 字节已经偏移过 typedef?struct?{ ????uint32_t????????????????????????????version_flags; 4 字节固定 ????uint32_t????????????????????????????entry_count; ????uint32_t????????????????????????????entries[0]; }?ngx_rtmp_mp4_offsets_t; typedef?struct?{ ????uint32_t????????????????????????????version_flags; ????uint32_t????????????????????????????entry_count; ????uint64_t????????????????????????????entries[0]; }?ngx_rtmp_mp4_offsets64_t;

三：数据结构解析

static?ngx_rtmp_mp4_box_t???????????????????????ngx_rtmp_mp4_boxes[]?=?{
????{?ngx_rtmp_mp4_make_tag('t','r','a','k'),???ngx_rtmp_mp4_parse_trak???},
????{?ngx_rtmp_mp4_make_tag('m','d','i','a'),???ngx_rtmp_mp4_parse????????},
????{?ngx_rtmp_mp4_make_tag('m','d','h','d'),???ngx_rtmp_mp4_parse_mdhd???},
????{?ngx_rtmp_mp4_make_tag('h','d','l','r'),???ngx_rtmp_mp4_parse_hdlr???},
????{?ngx_rtmp_mp4_make_tag('m','i','n','f'),???ngx_rtmp_mp4_parse????????},
????{?ngx_rtmp_mp4_make_tag('s','t','b','l'),???ngx_rtmp_mp4_parse????????},
????{?ngx_rtmp_mp4_make_tag('s','t','s','d'),???ngx_rtmp_mp4_parse_stsd???},
????{?ngx_rtmp_mp4_make_tag('s','t','s','c'),???ngx_rtmp_mp4_parse_stsc???},  // 记录了每个chunk中包含多少sample
????{?ngx_rtmp_mp4_make_tag('s','t','t','s'),???ngx_rtmp_mp4_parse_stts???},  // sample 解码时间的压缩表
????{?ngx_rtmp_mp4_make_tag('c','t','t','s'),???ngx_rtmp_mp4_parse_ctts???},  // 帧解码到渲染的时间差值，通常用在B帧的场景，sample的CTS与DTS的时间差的压缩表
????{?ngx_rtmp_mp4_make_tag('s','t','s','s'),???ngx_rtmp_mp4_parse_stss???},  // 关键帧映射表
????{?ngx_rtmp_mp4_make_tag('s','t','s','z'),???ngx_rtmp_mp4_parse_stsz???},  // 每帧数据的大小
????{?ngx_rtmp_mp4_make_tag('s','t','z','2'),???ngx_rtmp_mp4_parse_stz2???},
????{?ngx_rtmp_mp4_make_tag('s','t','c','o'),???ngx_rtmp_mp4_parse_stco???},  // 记录了chunk对应的offset
????{?ngx_rtmp_mp4_make_tag('c','o','6','4'),???ngx_rtmp_mp4_parse_co64???},
????{?ngx_rtmp_mp4_make_tag('a','v','c','1'),???ngx_rtmp_mp4_parse_avc1???},
????{?ngx_rtmp_mp4_make_tag('a','v','c','C'),???ngx_rtmp_mp4_parse_avcC???},   // sps pps 解析
????{?ngx_rtmp_mp4_make_tag('m','p','4','a'),???ngx_rtmp_mp4_parse_mp4a???},
????{?ngx_rtmp_mp4_make_tag('m','p','4','v'),???ngx_rtmp_mp4_parse_mp4v???},
????{?ngx_rtmp_mp4_make_tag('e','s','d','s'),???ngx_rtmp_mp4_parse_esds???},
????{?ngx_rtmp_mp4_make_tag('.','m','p','3'),???ngx_rtmp_mp4_parse_mp3????},
????{?ngx_rtmp_mp4_make_tag('n','m','o','s'),???ngx_rtmp_mp4_parse_nmos???},
????{?ngx_rtmp_mp4_make_tag('s','p','e','x'),???ngx_rtmp_mp4_parse_spex???},
????{?ngx_rtmp_mp4_make_tag('w','a','v','e'),???ngx_rtmp_mp4_parse????????}
};

ngx_rtmp_mp4_parse_stsc?? 记录了每个chunk中包含多少sample

上图数据解析

00 00 00 28(size) --> 40 字节总大小包含的自己在内的所有数据：

00 00 00 28(size) 73 74 73 63（stsc） 00 00 00 00(version_flags) 00 00 00 02(entry_count) 00 00 00 01(first_chunk) 00 00 00 02(samples_per_chunk) 00 00 00 01(sample_descrption_index) 00 00 00 02(first_chunk) 00 00 00 01(samples_per_chunk) 00 00 00 01(sample_descrption_index)

static?ngx_int_t
ngx_rtmp_mp4_parse_stsc(ngx_rtmp_session_t?*s,?u_char?*pos,?u_char?*last)
{
????ngx_rtmp_mp4_ctx_t?????????*ctx;
????ngx_rtmp_mp4_track_t???????*t;
????ctx?=?ngx_rtmp_get_module_ctx(s,?ngx_rtmp_mp4_module);
????t?=?ctx->track;
????if?(t?==?NULL)?{
????????return?NGX_OK;
????}
????t->chunks?=?(ngx_rtmp_mp4_chunks_t?*)?pos;  // 内存数据上面的解析
????if?(pos?+?sizeof(*t->chunks)?+?ngx_rtmp_r32(t->chunks->entry_count)?*
???????????????????????????????????sizeof(t->chunks->entries[0])
????????<=?last)// 内存越界判断
????{
????????return?NGX_OK;
????}
????t->chunks?=?NULL;
????return?NGX_ERROR;
}

ngx_rtmp_mp4_parse_stco? 记录了chunk对应的offset

00 00 03 D4（980 长度） 73 74 63 6F （stco）00 00 00 00(version_flags) 00 00 00 F1( entry_count 241 ) 00 00 00 30(?entrie) 00 00 10 4D (?entrie)00 00 20 1C(?entrie) 00 00 29 38(?entrie) 00 00 49 2D(?entrie) 00 00 70 C9(?entrie) 00 00 B1 C1 (?entrie) ...............

static?ngx_int_t
ngx_rtmp_mp4_parse_stco(ngx_rtmp_session_t?*s,?u_char?*pos,?u_char?*last)
{
????ngx_rtmp_mp4_ctx_t?????????*ctx;
????ngx_rtmp_mp4_track_t???????*t;
????ctx?=?ngx_rtmp_get_module_ctx(s,?ngx_rtmp_mp4_module);
????t?=?ctx->track;
????if?(t?==?NULL)?{
????????return?NGX_OK;
????}
????t->offsets?=?(ngx_rtmp_mp4_offsets_t?*)?pos; // 数据结构的赋值
????if?(pos?+?sizeof(*t->offsets)?+?ngx_rtmp_r32(t->offsets->entry_count)?*
????????????????????????????????????sizeof(t->offsets->entries[0])
????????<=?last) // 内存越界判断
????{
????????return?NGX_OK;
????}
????t->offsets?=?NULL;
????return?NGX_ERROR;
}

其他数据结构的解析与上面的流程基本一样

四：数据处理流程

五：play 流程代码分析

ffplay -analyzeduration 1000000 "rtmp://10.90.103.5/vod/0001.mp4

1> ngx_rtmp_mp4_init 初始化变量解析 mp4 moov box 的数据结构

2> ngx_rtmp_mp4_seek (ngx_rtmp_session_t?*s,?ngx_file_t?*f,?ngx_uint_t?timestamp)， timestamp = 0 ，seek 时间戳为零标识从头开始播放。ngx_rtmp_mp4_seek_track 有两个轨道，音频轨和视频轨，分别进行seek

static?ngx_int_t
ngx_rtmp_mp4_seek_track(ngx_rtmp_session_t?*s,?ngx_rtmp_mp4_track_t?*t,
????????????????????????ngx_int_t?timestamp)
{
????ngx_rtmp_mp4_cursor_t??????????*cr;
????cr?=?&t->cursor;
????ngx_memzero(cr,?sizeof(*cr));
????if?(ngx_rtmp_mp4_seek_time(s,?t,?ngx_rtmp_mp4_from_rtmp_timestamp(  // ngx_rtmp_mp4_from_rtmp_timestamp 时间戳的
??????????????????????????t,?timestamp))?!=?NGX_OK?||
????????ngx_rtmp_mp4_seek_key(s,?t)???!=?NGX_OK?||
????????ngx_rtmp_mp4_seek_chunk(s,?t)?!=?NGX_OK?||
????????ngx_rtmp_mp4_seek_size(s,?t)??!=?NGX_OK?||
????????ngx_rtmp_mp4_seek_delay(s,?t)?!=?NGX_OK)
????{
????????return?NGX_ERROR;
????}
????cr->valid?=?1;
????return?NGX_OK;
} 

// 时间戳的转换函数，mp4 文件到rtmp
// rtmp_mp4 存放的是timescale 时间戳 通常是 12288
// rtmp 时间刻度通常是 1000 
static?ngx_inline?uint32_t
ngx_rtmp_mp4_to_rtmp_timestamp(ngx_rtmp_mp4_track_t?*t,?uint64_t?ts) // 给定一个时间值 从rtmp_mp4 12288 刻度转换到 1000
{
????return?(uint32_t)?(ts?*?1000?/?t->time_scale); 
}
static?ngx_inline?uint32_t
ngx_rtmp_mp4_from_rtmp_timestamp(ngx_rtmp_mp4_track_t?*t,?uint32_t?ts) // 给定一个时间值 从rtmp 1000 刻度转换到12288
{
????return?(uint64_t)?ts?*?t->time_scale?/?1000;
}

ngx_rtmp_mp4_seek_time :

stts： typedef?struct?{ ????uint32_t????????????????????????????sample_count; ????uint32_t????????????????????????????sample_delta; }?ngx_rtmp_mp4_time_entry_t; typedef?struct?{ ????uint32_t????????????????????????????version_flags; ????uint32_t????????????????????????????entry_count; ????ngx_rtmp_mp4_time_entry_t???????????entries[0]; }?ngx_rtmp_mp4_times_t;

static?ngx_int_t
ngx_rtmp_mp4_seek_time(ngx_rtmp_session_t?*s,?ngx_rtmp_mp4_track_t?*t,
???????????????????????uint32_t?timestamp)
{
????ngx_rtmp_mp4_cursor_t??????*cr;
????ngx_rtmp_mp4_time_entry_t??*te;
????uint32_t????????????????????dt;
????if?(t->times?==?NULL)?{
????????return?NGX_ERROR;
????}
????cr?=?&t->cursor; // 对应音频或者视频轨道的游标器
????te?=?t->times->entries; // times --> ngx_rtmp_mp4_times_t
    // sample_counts	6,1,5,1,5,1,1,1,1,1
    // sample_deltas	1024,3040,1024,3088,1024,1008,1024,1032,1024,1048     
    // 整个循环就是处理，遍历sample_counts个sample_deltas值与 参数 timestamp比大小. 1. 小于记录 cr->timestamp?+=?dt,
????while?(cr->time_pos?<?ngx_rtmp_r32(t->times->entry_count))?{
????????dt?=?ngx_rtmp_r32(te->sample_delta)?*?ngx_rtmp_r32(te->sample_count); // 242 * 1024 = 22757376 
        // cr->timestamp?+?dt?>=?timestamp ，在这个范围说明找到
????????if?(cr->timestamp?+?dt?>=?timestamp)?{
????????????if?(te->sample_delta?==?0)?{
????????????????return?NGX_ERROR;
????????????}
????????????cr->time_count?=?(timestamp?-?cr->timestamp)?/
?????????????????????????????ngx_rtmp_r32(te->sample_delta);                   // sample_delta 相同，cr->time_count 等于当前时间戳距离这个entry开始时间错的插值，的第几个delta
????????????cr->timestamp?+=?ngx_rtmp_r32(te->sample_delta)?*?cr->time_count;  // seek 的时间戳，就是把 cr->timestamp 修改当前的时间戳
????????????cr->pos?+=?cr->time_count;                                         // 记录当前seek 对应时间戳具体的位置
????????????break;
????????}
        // 没找到，
????????cr->timestamp?+=?dt;                       // 记录值进行累加，访问下一个
????????cr->pos?+=?ngx_rtmp_r32(te->sample_count); // 记录pos 的位置
????????cr->time_pos++;                            // 记录已经访问第几个entry
????????te++;                                      // te++ 下一个entry
????}
????if?(cr->time_pos?>=?ngx_rtmp_r32(t->times->entry_count))?{
????????return??NGX_ERROR;
????}
????return?NGX_OK;
}

ngx_rtmp_mp4_seek_key

stss typedef?struct?{ ????uint32_t????????????????????????????version_flags; ????uint32_t????????????????????????????entry_count; // 个数 ????uint32_t????????????????????????????entries[0]; // pos }?ngx_rtmp_mp4_keys_t;

static?ngx_int_t
ngx_rtmp_mp4_seek_key(ngx_rtmp_session_t?*s,?ngx_rtmp_mp4_track_t?*t)
{
????ngx_rtmp_mp4_cursor_t??????*cr;
????uint32_t???????????????????*ke;
????ngx_int_t???????????????????dpos;
????cr?=?&t->cursor;       // 对应音频或者视频轨道的游标器
????if?(t->keys?==?NULL)?{
????????return?NGX_OK;
????}
    // cr->key_pos 初始值为0 ，t->keys->entry_count 关键帧的个数
????while?(cr->key_pos?<?ngx_rtmp_r32(t->keys->entry_count))?{
        // 遍历每一个entry得到帧号，与当前pos位置进行对比，找到当前位置的下一个关键帧
????????if?(ngx_rtmp_r32(t->keys->entries[cr->key_pos])?>?cr->pos)?{    // cr->pos 上面seek 后具体位置
????????????break;
????????}
????????cr->key_pos++;
????}
????if?(cr->key_pos?>=?ngx_rtmp_r32(t->keys->entry_count))?{
????????return?NGX_OK;
????}
????ke?=?&t->keys->entries[cr->key_pos];                                // 
????dpos?=?ngx_rtmp_r32(*ke)?-?cr->pos?-?1;                             // 计算距离下一个关键帧的差值
????cr->key?=?1;
????/*?TODO:?range?version?needed?*/
????for?(;?dpos?>?0;?--dpos)?{
????????ngx_rtmp_mp4_next_time(s,?t);
????}
????return?NGX_OK;
}

ngx_rtmp_mp4_seek_chunk

stsc typedef?struct?{ ????uint32_t????????????????????????????first_chunk; ????uint32_t????????????????????????????samples_per_chunk; ????uint32_t????????????????????????????sample_descrption_index; }?ngx_rtmp_mp4_chunk_entry_t; typedef?struct?{ ????uint32_t????????????????????????????version_flags; ????uint32_t????????????????????????????entry_count; ????ngx_rtmp_mp4_chunk_entry_t??????????entries[0]; }?ngx_rtmp_mp4_chunks_t;

static?ngx_int_t
ngx_rtmp_mp4_seek_chunk(ngx_rtmp_session_t?*s,?ngx_rtmp_mp4_track_t?*t)
{
????ngx_rtmp_mp4_cursor_t??????????*cr;
????ngx_rtmp_mp4_chunk_entry_t?????*ce,?*nce;
????ngx_uint_t??????????????????????pos,?dpos,?dchunk;
????cr?=?&t->cursor;                                              // 对应音频或者视频轨道的游标器
????if?(t->chunks?==?NULL?||?t->chunks->entry_count?==?0)?{
????????cr->chunk?=?1;
????????return?NGX_OK;
????}
????ce?=?t->chunks->entries;                                      // entry 实体结构  
????pos?=?0;
    // cr->chunk_pos 初始值是0 
????while?(cr->chunk_pos?+?1?<?ngx_rtmp_r32(t->chunks->entry_count))?{
????????nce?=?ce?+?1;                                             // 下一个entry
????????dpos?=?(ngx_rtmp_r32(nce->first_chunk)?-
????????????????ngx_rtmp_r32(ce->first_chunk))?*
????????????????ngx_rtmp_r32(ce->samples_per_chunk);              // 距离下一个chunk总共有多少点，（2-1） * 2 = 2 帧
????????if?(pos?+?dpos?>?cr->pos)?{                               // 判断当前位置是不是在这个chunk 中
????????????break;
????????}
????????pos?+=?dpos;                                              // pos 从头遍历累加 
????????ce++;                                                     // 访问下一个entry
????????cr->chunk_pos++;                                          // chunk_pos ++，记录游标当前在第几个chunk位置 
????}
????if?(ce->samples_per_chunk?==?0)?{
????????return?NGX_ERROR;
????}
????dchunk?=?(cr->pos?-?pos)?/?ngx_rtmp_r32(ce->samples_per_chunk); // seek 之后的当前pos 位置，与找到chunk的pos差值，相同连续的chunk 可能不记录写进去。
    // 比如:  first_chunk   1,2,3,4,5,6,12,13
    //  samples_per_chunk   1,4,2,4,2,4,3, 4      ---> 1 + 4 + 2 + 4 + 2 + 4 = 17 , 18 --> 38 之间都是; 这个时候会有一个 dchunk差值
    
????cr->chunk?=?ngx_rtmp_r32(ce->first_chunk)?+?dchunk;             // 得到当前游标chunk的值，真实对应chunk 位置。
????cr->chunk_pos?=?(ngx_uint_t)?(ce?-?t->chunks->entries);         // cr->chunk_pos 记录的是存储的真实解析位置
????cr->chunk_count?=?(ngx_uint_t)?(cr->pos?-?pos?-?dchunk?*
????????????????????????????????????ngx_rtmp_r32(ce->samples_per_chunk)); // 剩余是 chunk 偏移的变量帧
????return?ngx_rtmp_mp4_update_offset(s,?t);
}

static?ngx_int_t
ngx_rtmp_mp4_update_offset(ngx_rtmp_session_t?*s,?ngx_rtmp_mp4_track_t?*t)
{
????ngx_rtmp_mp4_cursor_t??????????*cr;
????ngx_uint_t??????????????????????chunk;
????cr?=?&t->cursor;
????if?(cr->chunk?<?1)?{
????????return?NGX_ERROR;
????}
????chunk?=?cr->chunk?-?1; // 数组访问 -1  
????if?(t->offsets)?{
????????if?(chunk?>=?ngx_rtmp_r32(t->offsets->entry_count))?{
????????????return?NGX_ERROR;
????????}
????????cr->offset?=?(off_t)?ngx_rtmp_r32(t->offsets->entries[chunk]); // 取出第几个chunk偏移大小进行赋值
????????cr->size?=?0;
????????return?NGX_OK;
????}
????if?(t->offsets64)?{
????????if?(chunk?>=?ngx_rtmp_r32(t->offsets64->entry_count))?{
????????????return?NGX_ERROR;
????????}
????????cr->offset?=?(off_t)?ngx_rtmp_r64(t->offsets64->entries[chunk]);
????????cr->size?=?0;
????????return?NGX_OK;
????}
????return?NGX_ERROR;
}

ngx_rtmp_mp4_seek_size

stsz typedef?struct?{ ????uint32_t????????????????????????????version_flags; 4 字节 ????uint32_t????????????????????????????sample_size; ????uint32_t????????????????????????????sample_count; ????uint32_t????????????????????????????entries[0]; }?ngx_rtmp_mp4_sizes_t;

static?ngx_int_t
ngx_rtmp_mp4_seek_size(ngx_rtmp_session_t?*s,?ngx_rtmp_mp4_track_t?*t)
{
????ngx_rtmp_mp4_cursor_t??????*cr;
????ngx_uint_t??????????????????pos;
????cr?=?&t->cursor;                                             // 当前游标
????if?(cr->chunk_count?>?cr->pos)?{                             // 》 ？？
????????return?NGX_ERROR;
????}
????if?(t->sizes)?{
????????if?(t->sizes->sample_size)?{
????????????cr->size?=?ngx_rtmp_r32(t->sizes->sample_size);
????????????cr->offset?+=?cr->size?*?cr->chunk_count;
????????????return?NGX_OK;
????????}
????????if?(cr->pos?>=?ngx_rtmp_r32(t->sizes->sample_count))?{
????????????return?NGX_ERROR;
????????}
????????for?(pos?=?1;?pos?<=?cr->chunk_count;?++pos)?{           // chunk_count ??
????????????cr->offset?+=?ngx_rtmp_r32(t->sizes->entries[cr->pos?-?pos]); 
????????}
????????cr->size_pos?=?cr->pos;                                   // seek 时间戳当前pos
????????cr->size?=?ngx_rtmp_r32(t->sizes->entries[cr->size_pos]); // 获取当前pos对应帧数据大小
????????return?NGX_OK;
????}
????if?(t->sizes2)?{
????????if?(cr->size_pos?>=?ngx_rtmp_r32(t->sizes2->sample_count))?{
????????????return?NGX_ERROR;
????????}
????????cr->size_pos?=?cr->pos;
????????return?NGX_OK;
????}
????return?NGX_ERROR;
}

ngx_rtmp_mp4_seek_delay

ctts typedef?struct?{ ????uint32_t????????????????????????????sample_count; ????uint32_t????????????????????????????sample_offset; }?ngx_rtmp_mp4_delay_entry_t; typedef?struct?{ ????uint32_t????????????????????????????version_flags; ????uint32_t????????????????????????????entry_count; ????ngx_rtmp_mp4_delay_entry_t??????????entries[0]; }?ngx_rtmp_mp4_delays_t;

static?ngx_int_t
ngx_rtmp_mp4_seek_delay(ngx_rtmp_session_t?*s,?ngx_rtmp_mp4_track_t?*t)
{
????ngx_rtmp_mp4_cursor_t??????*cr;
????ngx_rtmp_mp4_delay_entry_t?*de;
????uint32_t????????????????????pos,?dpos;
????cr?=?&t->cursor;
????if?(t->delays?==?NULL)?{
????????return?NGX_OK;
????}
????pos?=?0;
????de?=?t->delays->entries;
????while?(cr->delay_pos?<?ngx_rtmp_r32(t->delays->entry_count))?{ // 遍历所有entry
????????dpos?=?ngx_rtmp_r32(de->sample_count);                     // 2 表示：sample的个数
????????if?(pos?+?dpos?>?cr->pos)?{                                // 0 + 2 > 0 , 当前pos 帧在其中
????????????cr->delay_count?=?cr->pos?-?pos;                       // 差值 count
????????????cr->delay?=?ngx_rtmp_r32(de->sample_offset);           // 偏移大小
????????????break;
????????}
????????cr->delay_pos++; // 记录entry访问的位置
????????pos?+=?dpos;     // pos 累加计数
????????de++;            // 下一个entry
????}
????if?(cr->delay_pos?>=?ngx_rtmp_r32(t->delays->entry_count))?{
????????return?NGX_OK;
????}
????return?NGX_OK;
}

3> ngx_rtmp_mp4_next play 播放一直取下一帧数据

static?ngx_int_t
ngx_rtmp_mp4_next(ngx_rtmp_session_t?*s,?ngx_rtmp_mp4_track_t?*t)
{
????if?(ngx_rtmp_mp4_next_time(s,?t)??!=?NGX_OK?||
????????ngx_rtmp_mp4_next_key(s,?t)???!=?NGX_OK?||
????????ngx_rtmp_mp4_next_chunk(s,?t)?!=?NGX_OK?||
????????ngx_rtmp_mp4_next_size(s,?t)??!=?NGX_OK?||
????????ngx_rtmp_mp4_next_delay(s,?t)?!=?NGX_OK)
????{
????????t->cursor.valid?=?0;
????????return?NGX_ERROR;
????}
????t->cursor.valid?=?1;
????return?NGX_OK;
}

六：代码调试

使用进行查看变量的值： ngx_rtmp_r32(t->delays->entry_count)