myvtm/Other/libmediaplayer/demux.cpp

#include "demux.h"
#include "packet.h"

#ifndef RVC_MAX_BUFFER_LEN
#define RVC_MAX_BUFFER_LEN 1024
#endif

static int decode_interrupt_cb(void *ctx)
{
    player_stat_t *is = (player_stat_t*)ctx;
    //return (int)(is->bvideo_finished && is->baudio_finished);
	return (int)(is->buser_stop);
}

static int demux_init(player_stat_t *is)
{
	int ret = -1;
	for (int index = 0; index < is->m_uFilesCount; index++)
	{
		AVFormatContext* p_fmt_ctx = NULL;
		int err = -1;
		int a_idx = -1;
		int v_idx = -1;

		p_fmt_ctx = avformat_alloc_context();
		if (!p_fmt_ctx){
			is->rvc_hostapi->Debug(MEDIA_LOG_ERROR, "Could not allocate context.");
			ret = AVERROR(ENOMEM);
			break;
		}
		// 中断回调机制。为底层I/O层提供一个处理接口，比如中止IO操作。
		p_fmt_ctx->interrupt_callback.callback = decode_interrupt_cb;
		p_fmt_ctx->interrupt_callback.opaque = is;
		// 1. 构建AVFormatContext
		// 1.1 打开视频文件：读取文件头，将文件格式信息存储在"fmt context"中
		err = avformat_open_input(&p_fmt_ctx, is->m_strPlayLists[index], NULL, NULL);
		if (err < 0){
			char buffer[RVC_MAX_BUFFER_LEN] = { 0 };
			av_strerror(err, buffer, RVC_MAX_BUFFER_LEN);
			is->rvc_hostapi->Debug(MEDIA_LOG_ERROR, "avformat_open_input file %s failed %d(%s).", is->m_strPlayLists[index], err, buffer);
			avformat_close_input(&p_fmt_ctx);
			avformat_free_context(p_fmt_ctx);
			ret = -1;
			break;
		}
		is->m_pfmt_ctx[index] = p_fmt_ctx;

		// 1.2 搜索流信息：读取一段视频文件数据，尝试解码，将取到的流信息填入p_fmt_ctx->streams
		//     ic->streams是一个指针数组，数组大小是pFormatCtx->nb_streams
		err = avformat_find_stream_info(p_fmt_ctx, NULL);
		if (err < 0){
			char strbuffer[RVC_MAX_BUFFER_LEN] = { 0 };
			av_strerror(err, strbuffer, RVC_MAX_BUFFER_LEN);
			is->rvc_hostapi->Debug(MEDIA_LOG_ERROR, "%s avformat_find_stream_info() failed %d(%s).", is->m_strPlayLists[index], err, strbuffer);
			avformat_close_input(&p_fmt_ctx);
			avformat_free_context(p_fmt_ctx);
			ret = -1;
			break;
		}

		// 2. 查找第一个音频流/视频流
		for (int i = 0; i < (int)p_fmt_ctx->nb_streams; i++){
			if ((p_fmt_ctx->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_AUDIO) && (a_idx == -1)){
				a_idx = i;
			}
			if ((p_fmt_ctx->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_VIDEO) && (v_idx == -1)){
				v_idx = i;
			}
			if (a_idx != -1 && v_idx != -1){
				break;
			}
		}

		if ((a_idx == -1 && v_idx == -1) || (eVideo_Type == is->m_eMType && v_idx == -1)){
			is->rvc_hostapi->Debug(MEDIA_LOG_ERROR, "Invalid file %s can not find any audio/video stream.", is->m_strPlayLists[index]);
			ret = -1;
			if (NULL != p_fmt_ctx){
				avformat_close_input(&p_fmt_ctx);
				avformat_free_context(p_fmt_ctx);
				is->m_pfmt_ctx[index] = NULL;
			}
			break;
		}

		is->audio_idx[index] = a_idx;
		is->video_idx[index] = v_idx;
		is->m_paudio_stream[index] = p_fmt_ctx->streams[a_idx];
		is->m_pvideo_stream[index] = p_fmt_ctx->streams[v_idx];
		
		ret = 0;
	}

    return ret;
}

int demux_deinit()
{
    return 0;
}

static int stream_has_enough_packets(AVStream *st, int stream_id, packet_queue_t *queue)
{
    return stream_id < 0 ||
           queue->abort_flag ||
           (st->disposition & AV_DISPOSITION_ATTACHED_PIC) ||
           queue->nb_packets > MIN_FRAMES && (!queue->duration || av_q2d(st->time_base) * queue->duration > 1.0);
}

/* this thread gets the stream from the disk or the network */
static int demux_thread(void *arg)
{
    player_stat_t *is = (player_stat_t *)arg;

    int ret = 0;
    
	AVPacket pkt1, *pkt = &pkt1;
    SDL_mutex *wait_mutex = SDL_CreateMutex();

    // 4. 解复用处理
	while (false == is->buser_stop)
    {
        /* if the queue are full, no need to read more */
        if (is->audio_pkt_queue.packet_queue_size + is->video_pkt_queue.packet_queue_size > MAX_QUEUE_SIZE ||
            (stream_has_enough_packets(is->m_paudio_stream[is->m_icurrent_index], is->audio_idx[is->m_icurrent_index], &is->audio_pkt_queue) &&
             stream_has_enough_packets(is->m_pvideo_stream[is->m_icurrent_index], is->video_idx[is->m_icurrent_index], &is->video_pkt_queue)))
        {
            /* wait 10 ms */
            SDL_LockMutex(wait_mutex);
            SDL_CondWaitTimeout(is->m_continue_read_thread, wait_mutex, 10);
            SDL_UnlockMutex(wait_mutex);
            continue;
        }

        // 4.1 从输入文件中读取一个packet
        ret = av_read_frame(is->m_pfmt_ctx[is->m_icurrent_index], pkt);
        if (ret < 0)
        {
            if (AVERROR_EOF == ret)
            {
                // 输入文件已读完，则往packet队列中发送NULL packet，以冲洗(flush)解码器，否则解码器中缓存的帧取不出来
                if (is->video_idx[is->m_icurrent_index] >= 0){
                    packet_queue_put_nullpacket(&is->video_pkt_queue, is->video_idx[is->m_icurrent_index], is->rvc_hostapi);
                }
                if (is->audio_idx[is->m_icurrent_index] >= 0){
                    packet_queue_put_nullpacket(&is->audio_pkt_queue, is->audio_idx[is->m_icurrent_index], is->rvc_hostapi);
                }

				if (is->m_icurrent_index + 1 < is->m_uFilesCount){
					is->m_icurrent_index++;
					ret = 0;
				}
				else {
					break;
				}
            }

            SDL_LockMutex(wait_mutex);
            SDL_CondWaitTimeout(is->m_continue_read_thread, wait_mutex, 10);
            SDL_UnlockMutex(wait_mutex);
            continue;
        }
        
        // 4.3 根据当前packet类型(音频、视频、字幕)，将其存入对应的packet队列
        if (pkt->stream_index == is->audio_idx[is->m_icurrent_index]){
            packet_queue_put(&is->audio_pkt_queue, pkt, is->rvc_hostapi);
        }
        else if (pkt->stream_index == is->video_idx[is->m_icurrent_index]){
            packet_queue_put(&is->video_pkt_queue, pkt, is->rvc_hostapi);
        }
        else{
            av_packet_unref(pkt);
        }
    }

    SDL_DestroyMutex(wait_mutex);

    return 0;
}


int open_demux(player_stat_t *is)
{
    if (demux_init(is) != 0){
		is->rvc_hostapi->Debug(MEDIA_LOG_ERROR, "demux_init() failed.");
        return -1;
    }

    is->m_read_tid = SDL_CreateThread(demux_thread, "demux_thread", is);
    if (is->m_read_tid == NULL){
		is->rvc_hostapi->Debug(MEDIA_LOG_ERROR, "SDL_CreateThread() failed: %s.", SDL_GetError());
        return -1;
    }

    return 0;
}