ffmpeg解碼視訊檔案並播放
阿新 • • 發佈：2018-12-09
最近學習了一下如何使用ffmpeg解碼音視訊，網上的教程挺多但是也挺雜的，搞了好幾天，明白了ffmpeg解碼音視訊的大體流程，這裡記錄一下ffmpeg解碼視訊並播放音視訊的例子，但並沒有做音訊、視訊播放 的同步處理。
直接上程式碼:
#include <iostream> #include <opencv2/opencv.hpp> #ifdef __cplusplus extern "C"{ #endif #include <libavcodec/avcodec.h> #include <libavformat/avformat.h> #include <libswscale/swscale.h> #include <libswresample/swresample.h> #ifdef __cplusplus } #endif #include <alsa/asoundlib.h> #define FALSE 0 #define TRUE 1 snd_pcm_t *handle; snd_pcm_hw_params_t *params; snd_pcm_uframes_t frames = 1024;//一個週期多少幀 snd_pcm_access_t access_mode = SND_PCM_ACCESS_RW_INTERLEAVED;//訪問模式:交錯訪問 snd_pcm_format_t format = SND_PCM_FORMAT_S16_LE;//取樣位數:16位,小端儲存 int channel = 2; unsigned int simple_rate = 44100;//取樣率 //int dir;//裝置取樣率與輸入取樣的偏差 char *buffer = NULL;//緩衝區資料 int size;//緩衝區大小 bool have_data = false; bool end_mark = false; const char *in_filename = "HelloVenus.mp4";//輸入URL(mov\mkv\ts\mp4\h264） const char *out_filename = "rtmp://123.206.23.239:1935/wstv/home";//輸出URL(rtmp://123.206.23.239:1935/wstv/home或rtp://233.233.233.233:6666) bool YUV2RGB(uchar* pYuvBuf, int nWidth, int nHeight, int channels, uchar* pRgbBuf) { #define PIXELSIZE nWidth * nHeight const int Table_fv1[256] = { -180, -179, -177, -176, -174, -173, -172, -170, -169, -167, -166, -165, -163, -162, -160, -159, -158, -156, -155, -153, -152, -151, -149, -148, -146, -145, -144, -142, -141, -139, -138, -137, -135, -134, -132, -131, -130, -128, -127, -125, -124, -123, -121, -120, -118, -117, -115, -114, -113, -111, -110, -108, -107, -106, -104, -103, -101, -100, -99, -97, -96, -94, -93, -92, -90, -89, -87, -86, -85, -83, -82, -80, -79, -78, -76, -75, -73, -72, -71, -69, -68, -66, -65, -64, -62, -61, -59, -58, -57, -55, -54, -52, -51, -50, -48, -47, -45, -44, -43, -41, -40, -38, -37, -36, -34, -33, -31, -30, -29, -27, -26, -24, -23, -22, -20, -19, -17, -16, -15, -13, -12, -10, -9, -8, -6, -5, -3, -2, 0, 1, 2, 4, 5, 7, 8, 9, 11, 12, 14, 15, 16, 18, 19, 21, 22, 23, 25, 26, 28, 29, 30, 32, 33, 35, 36, 37, 39, 40, 42, 43, 44, 46, 47, 49, 50, 51, 53, 54, 56, 57, 58, 60, 61, 63, 64, 65, 67, 68, 70, 71, 72, 74, 75, 77, 78, 79, 81, 82, 84, 85, 86, 88, 89, 91, 92, 93, 95, 96, 98, 99, 100, 102, 103, 105, 106, 107, 109, 110, 112, 113, 114, 116, 117, 119, 120, 122, 123, 124, 126, 127, 129, 130, 131, 133, 134, 136, 137, 138, 140, 141, 143, 144, 145, 147, 148, 150, 151, 152, 154, 155, 157, 158, 159, 161, 162, 164, 165, 166, 168, 169, 171, 172, 173, 175, 176, 178 }; const int Table_fv2[256] = { -92, -91, -91, -90, -89, -88, -88, -87, -86, -86, -85, -84, -83, -83, -82, -81, -81, -80, -79, -78, -78, -77, -76, -76, -75, -74, -73, -73, -72, -71, -71, -70, -69, -68, -68, -67, -66, -66, -65, -64, -63, -63, -62, -61, -61, -60, -59, -58, -58, -57, -56, -56, -55, -54, -53, -53, -52, -51, -51, -50, -49, -48, -48, -47, -46, -46, -45, -44, -43, -43, -42, -41, -41, -40, -39, -38, -38, -37, -36, -36, -35, -34, -33, -33, -32, -31, -31, -30, -29, -28, -28, -27, -26, -26, -25, -24, -23, -23, -22, -21, -21, -20, -19, -18, -18, -17, -16, -16, -15, -14, -13, -13, -12, -11, -11, -10, -9, -8, -8, -7, -6, -6, -5, -4, -3, -3, -2, -1, 0, 0, 1, 2, 2, 3, 4, 5, 5, 6, 7, 7, 8, 9, 10, 10, 11, 12, 12, 13, 14, 15, 15, 16, 17, 17, 18, 19, 20, 20, 21, 22, 22, 23, 24, 25, 25, 26, 27, 27, 28, 29, 30, 30, 31, 32, 32, 33, 34, 35, 35, 36, 37, 37, 38, 39, 40, 40, 41, 42, 42, 43, 44, 45, 45, 46, 47, 47, 48, 49, 50, 50, 51, 52, 52, 53, 54, 55, 55, 56, 57, 57, 58, 59, 60, 60, 61, 62, 62, 63, 64, 65, 65, 66, 67, 67, 68, 69, 70, 70, 71, 72, 72, 73, 74, 75, 75, 76, 77, 77, 78, 79, 80, 80, 81, 82, 82, 83, 84, 85, 85, 86, 87, 87, 88, 89, 90, 90 }; const int Table_fu1[256] = { -44, -44, -44, -43, -43, -43, -42, -42, -42, -41, -41, -41, -40, -40, -40, -39, -39, -39, -38, -38, -38, -37, -37, -37, -36, -36, -36, -35, -35, -35, -34, -34, -33, -33, -33, -32, -32, -32, -31, -31, -31, -30, -30, -30, -29, -29, -29, -28, -28, -28, -27, -27, -27, -26, -26, -26, -25, -25, -25, -24, -24, -24, -23, -23, -22, -22, -22, -21, -21, -21, -20, -20, -20, -19, -19, -19, -18, -18, -18, -17, -17, -17, -16, -16, -16, -15, -15, -15, -14, -14, -14, -13, -13, -13, -12, -12, -11, -11, -11, -10, -10, -10, -9, -9, -9, -8, -8, -8, -7, -7, -7, -6, -6, -6, -5, -5, -5, -4, -4, -4, -3, -3, -3, -2, -2, -2, -1, -1, 0, 0, 0, 1, 1, 1, 2, 2, 2, 3, 3, 3, 4, 4, 4, 5, 5, 5, 6, 6, 6, 7, 7, 7, 8, 8, 8, 9, 9, 9, 10, 10, 11, 11, 11, 12, 12, 12, 13, 13, 13, 14, 14, 14, 15, 15, 15, 16, 16, 16, 17, 17, 17, 18, 18, 18, 19, 19, 19, 20, 20, 20, 21, 21, 22, 22, 22, 23, 23, 23, 24, 24, 24, 25, 25, 25, 26, 26, 26, 27, 27, 27, 28, 28, 28, 29, 29, 29, 30, 30, 30, 31, 31, 31, 32, 32, 33, 33, 33, 34, 34, 34, 35, 35, 35, 36, 36, 36, 37, 37, 37, 38, 38, 38, 39, 39, 39, 40, 40, 40, 41, 41, 41, 42, 42, 42, 43, 43 }; const int Table_fu2[256] = { -227, -226, -224, -222, -220, -219, -217, -215, -213, -212, -210, -208, -206, -204, -203, -201, -199, -197, -196, -194, -192, -190, -188, -187, -185, -183, -181, -180, -178, -176, -174, -173, -171, -169, -167, -165, -164, -162, -160, -158, -157, -155, -153, -151, -149, -148, -146, -144, -142, -141, -139, -137, -135, -134, -132, -130, -128, -126, -125, -123, -121, -119, -118, -116, -114, -112, -110, -109, -107, -105, -103, -102, -100, -98, -96, -94, -93, -91, -89, -87, -86, -84, -82, -80, -79, -77, -75, -73, -71, -70, -68, -66, -64, -63, -61, -59, -57, -55, -54, -52, -50, -48, -47, -45, -43, -41, -40, -38, -36, -34, -32, -31, -29, -27, -25, -24, -22, -20, -18, -16, -15, -13, -11, -9, -8, -6, -4, -2, 0, 1, 3, 5, 7, 8, 10, 12, 14, 15, 17, 19, 21, 23, 24, 26, 28, 30, 31, 33, 35, 37, 39, 40, 42, 44, 46, 47, 49, 51, 53, 54, 56, 58, 60, 62, 63, 65, 67, 69, 70, 72, 74, 76, 78, 79, 81, 83, 85, 86, 88, 90, 92, 93, 95, 97, 99, 101, 102, 104, 106, 108, 109, 111, 113, 115, 117, 118, 120, 122, 124, 125, 127, 129, 131, 133, 134, 136, 138, 140, 141, 143, 145, 147, 148, 150, 152, 154, 156, 157, 159, 161, 163, 164, 166, 168, 170, 172, 173, 175, 177, 179, 180, 182, 184, 186, 187, 189, 191, 193, 195, 196, 198, 200, 202, 203, 205, 207, 209, 211, 212, 214, 216, 218, 219, 221, 223, 225 }; int len = channels * nWidth * nHeight; if (!pYuvBuf || !pRgbBuf) return false; const long nYLen = long(PIXELSIZE); const int nHfWidth = (nWidth >> 1); if (nYLen<1 || nHfWidth<1) return false; // Y data unsigned char* yData = pYuvBuf; // v data unsigned char* vData = &yData[nYLen]; // u data unsigned char* uData = &vData[nYLen >> 2]; if (!uData || !vData) return false; int rgb[3]; int i, j, m, n, x, y, pu, pv, py, rdif, invgdif, bdif; m = -nWidth; n = -nHfWidth; bool addhalf = true; for (y = 0; y<nHeight; y++) { m += nWidth; if (addhalf) { n += nHfWidth; addhalf = false; } else { addhalf = true; } for (x = 0; x<nWidth; x++) { i = m + x; j = n + (x >> 1); py = yData[i]; // search tables to get rdif invgdif and bidif rdif = Table_fv1[vData[j]]; // fv1 invgdif = Table_fu1[uData[j]] + Table_fv2[vData[j]]; // fu1+fv2 bdif = Table_fu2[uData[j]]; // fu2 rgb[0] = py + rdif; // R rgb[1] = py - invgdif; // G rgb[2] = py + bdif; // B j = nYLen - nWidth - m + x; i = (j << 1) + j; // copy this pixel to rgb data for (j = 0; j<3; j++) { if (rgb[j] >= 0 && rgb[j] <= 255) { pRgbBuf[i + j] = rgb[j]; } else { pRgbBuf[i + j] = (rgb[j] < 0) ? 0 : 255; } } } } return true; } void AVFrame2Img(AVFrame *pFrame, cv::Mat& img) { int frameHeight = pFrame->height; int frameWidth = pFrame->width; int channels = 3; //輸出影象分配記憶體 img = cv::Mat::zeros(frameHeight, frameWidth, CV_8UC3); //反轉影象 pFrame->data[0] += pFrame->linesize[0] * (frameHeight - 1); pFrame->linesize[0] *= -1; pFrame->data[1] += pFrame->linesize[1] * (frameHeight / 2 - 1); pFrame->linesize[1] *= -1; pFrame->data[2] += pFrame->linesize[2] * (frameHeight / 2 - 1); pFrame->linesize[2] *= -1; //建立儲存yuv資料的buffer uchar* pDecodedBuffer = (uchar*)malloc(frameHeight*frameWidth * sizeof(uchar)*channels); //從AVFrame中獲取yuv420p資料，並儲存到buffer int i, j, k; //拷貝y分量 for (i = 0; i < frameHeight; i++) { memcpy(pDecodedBuffer + frameWidth*i, pFrame->data[0] + pFrame->linesize[0] * i, frameWidth); } //拷貝u分量 for (j = 0; j < frameHeight / 2; j++) { memcpy(pDecodedBuffer + frameWidth*i + frameWidth / 2 * j, pFrame->data[1] + pFrame->linesize[1] * j, frameWidth / 2); } //拷貝v分量 for (k = 0; k < frameHeight / 2; k++) { memcpy(pDecodedBuffer + frameWidth*i + frameWidth / 2 * j + frameWidth / 2 * k, pFrame->data[2] + pFrame->linesize[2] * k, frameWidth / 2); } //將buffer中的yuv420p資料轉換為RGB; YUV2RGB(pDecodedBuffer, frameWidth, frameHeight, channels, img.data); //釋放buffer free(pDecodedBuffer); } int ffmpeg_decode() { //1. 首先註冊ffmpeg所有的編解碼器 av_register_all(); //2.1 開啟輸入檔案 AVFormatContext* avFormatContext = avformat_alloc_context(); int ret = avformat_open_input(&avFormatContext, in_filename, NULL, NULL);//讀取檔案頭 if( ret != 0 ){ printf("Couldn't open input file.\n"); return -1; } //2.2 獲取流資訊 ret = avformat_find_stream_info(avFormatContext, NULL); if( ret < 0 ){//獲取檔案中的流資訊 printf("Couldn't get input file infomation.\n"); return -1; } //2.3 列印檔案的詳細資訊 av_dump_format(avFormatContext, -1, in_filename, 0); //3. 獲取對應流的索引號 int videoStream_index = -1;//視訊流索引號 int audioStream_index = -1;//音訊流索引號 for(int i = 0; i < avFormatContext->nb_streams; i++ ){ if(avFormatContext->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO){ videoStream_index = i; } if(avFormatContext->streams[i]->codec->codec_type == AVMEDIA_TYPE_AUDIO){ audioStream_index = i; } } if( videoStream_index == -1 || audioStream_index == -1 ){ printf("Couldn't get input file videoStream or audioStream!\n"); return -1; } //3.1 獲取視訊流的編碼上下文 AVCodecContext* videoCodecContext = avFormatContext->streams[videoStream_index]->codec; AVCodec* videoCodec = avcodec_find_decoder(videoCodecContext->codec_id);//通過上下文查詢編碼器 if( videoCodec == NULL ){ printf("Couldn't get AVCodec\n"); return -1; } if( avcodec_open2(videoCodecContext, videoCodec, NULL) < 0 ){// 開啟編碼器 printf("Couldn't open AVCodec\n"); return -1; } //3.2 獲取音訊流的編解碼上下文 AVCodecContext* audioCodecContext = avFormatContext->streams[audioStream_index]->codec; AVCodec* audioCodec = avcodec_find_decoder(audioCodecContext->codec_id);//通過上下文查詢編碼器 if( audioCodec == NULL ){ printf("Couldn't get AVCodec\n"); return -1; } if( avcodec_open2(audioCodecContext, audioCodec, NULL) < 0 ){// 開啟編碼器 printf("Couldn't open AVCodec\n"); return -1; } simple_rate = audioCodecContext->sample_rate;//取樣率(音訊) printf("simple_rate=%d\n",simple_rate); channel = audioCodecContext->channels;//聲道數(音訊) printf("channel=%d\n",channel); switch (audioCodecContext->sample_fmt) {//取樣格式 case AV_SAMPLE_FMT_U8: format = SND_PCM_FORMAT_U8;//8位 printf("sample_fmt=%d\n",SND_PCM_FORMAT_U8); break; case AV_SAMPLE_FMT_S16: format = SND_PCM_FORMAT_S16_LE;//16位 printf("sample_fmt=%d\n",SND_PCM_FORMAT_S16_LE); break; } /* 1. 開啟pcm裝置 */ int rc = snd_pcm_open(&handle, "default",SND_PCM_STREAM_PLAYBACK, 0); if (rc < 0) { printf("open device failed\n"); return FALSE; } /* 2. 分配一個硬體引數物件 */ snd_pcm_hw_params_alloca(¶ms); snd_pcm_hw_params_any(handle, params);/* 使用預設值填充引數物件. */ /* 設定硬體引數 */ snd_pcm_hw_params_set_access(handle, params,access_mode);/* 交錯模式 Interleaved mode */ snd_pcm_hw_params_set_format(handle, params,format);/* 取樣位數 Signed 16-bit little-endian format */ snd_pcm_hw_params_set_channels(handle, params, channel);/* 通道數 Two channels (stereo) */ snd_pcm_hw_params_set_rate_near(handle, params,&simple_rate, NULL);/* 取樣率 44100 bits/second sampling rate (CD quality) */ snd_pcm_hw_params_set_period_size_near(handle,params, &frames, NULL);//設定一個週期的多少幀 rc = snd_pcm_hw_params(handle, params);/* 將設定好的引數寫入驅動 */ if (rc < 0) { printf("unable to set hw parameters: %s\n",snd_strerror(rc)); return FALSE; } /* 獲取一個週期的大小(幀) Use a buffer large enough to hold one period */ snd_pcm_hw_params_get_period_size(params, &frames,NULL); printf("frames = %ld\n",frames); //4.1 開始讀取資料 AVPacket *avPacket = (AVPacket*)av_malloc(sizeof(AVPacket));//分配avPacket AVFrame *videoFrame = av_frame_alloc();//分配視訊幀 AVFrame *audioFrame = av_frame_alloc();//分配音訊幀 unsigned int buffer_size = 2*2*44100; // uint8_t *out_buffer = (uint8_t*)av_malloc(buffer_size); /*對解碼的資料進行重新取樣*/ SwrContext *swrCtx = swr_alloc(); enum AVSampleFormat in_sample_fmt = audioCodecContext->sample_fmt; //輸入的取樣格式 enum AVSampleFormat out_sample_fmt = AV_SAMPLE_FMT_S16; //輸出的取樣格式 16bit PCM int in_sample_rate = audioCodecContext->sample_rate; //輸入的取樣率 int out_sample_rate = 44100; //輸出的取樣率 uint64_t in_ch_layout = audioCodecContext->channel_layout; //輸入的聲道佈局 uint64_t out_ch_layout = AV_CH_LAYOUT_STEREO; //輸出的聲道佈局 swr_alloc_set_opts(swrCtx, out_ch_layout, //輸出通道佈局 out_sample_fmt, //輸出取樣格式 out_sample_rate,//輸出取樣率 in_ch_layout, //輸入取樣佈局 in_sample_fmt, //輸入取樣格式 in_sample_rate, //輸入取樣率 0, //logging level offset NULL);//parent logging context, can be NULL swr_init(swrCtx); //建立影象格式轉換上下文 SwsContext *rgbSwsContext = sws_getContext(videoCodecContext->width,//原影象寬 videoCodecContext->height,//原影象高 videoCodecContext->pix_fmt,//原影象格式 640,//目標影象寬 480,//目標影象高 AV_PIX_FMT_BGR24,//目標影象格式 SWS_BICUBIC,//轉換演算法 NULL,//原影象濾波 NULL,//目標影象濾波 NULL);//其他引數 //轉換後的影象資料緩衝區 AVFrame* rgbFrame = av_frame_alloc(); //影象緩衝區大小 int rgbBuffer_size=avpicture_get_size(AV_PIX_FMT_BGR24, videoCodecContext->width,videoCodecContext->height); uint8_t* rgbBuffer=(uint8_t*)av_malloc(rgbBuffer_size*sizeof(uint8_t)); avpicture_fill((AVPicture *)rgbFrame, rgbBuffer, AV_PIX_FMT_BGR24,videoCodecContext->width, videoCodecContext->height); while (av_read_frame(avFormatContext,avPacket) >= 0) { if(avPacket->stream_index == videoStream_index){ int got_picture_ptr = 0;//是否被解碼成功解碼的標識(0標識失敗,非0表示成功) avcodec_decode_video2(videoCodecContext,videoFrame,&got_picture_ptr,avPacket);//解碼視訊幀 if(0 != got_picture_ptr) { // sws_scale(rgbSwsContext, //轉換上下文 // (uint8_t const * const *)videoFrame->data, //輸入影象資料 // videoFrame->linesize, //輸入影象行尺寸(寬度) // 0, //第一列要處理的位置(從第幾行資料開始處理) // videoFrame->height, //輸入影象高度 // rgbFrame->data, //輸出影象資料 // rgbFrame->linesize); //輸出影象行尺寸(寬度) cv::Mat mat = cv::Mat(cv::Size(640,480),CV_8UC3); AVFrame2Img(videoFrame,mat); cv::imshow("picture",mat); cv::waitKey(15); std::cout<<"視訊解碼成功:"<<videoFrame->format<<std::endl; } } if(avPacket->stream_index == audioStream_index){ int got_frame_ptr = 0;//是否被解碼成功的標識 avcodec_decode_audio4(audioCodecContext,audioFrame,&got_frame_ptr,avPacket);//解碼音訊幀 if(0 != got_frame_ptr) { swr_convert(swrCtx, //轉換上下文 &out_buffer, //輸出buff buffer_size, //輸出空間大小 (const uint8_t**)audioFrame->data, //輸入buffer audioFrame->nb_samples); //取樣數量 /*將音訊資料餵給裝置*/ rc = snd_pcm_writei(handle, out_buffer, audioFrame->nb_samples); if (rc == -EPIPE){ printf("underrun occurred\n");/* EPIPE means underrun */ snd_pcm_prepare(handle); }else if (rc < 0){ printf("error from writei: %s\n",snd_strerror(rc)); } printf("音訊解碼成功:frames=%d -- nb_samples=%d\n",frames,audioFrame->nb_samples); } } } av_free(rgbBuffer);//釋放緩衝區資料 av_frame_free(&rgbFrame);//釋放RGBFrame sws_freeContext(rgbSwsContext);//釋放影象轉換上下文 av_free(out_buffer);//釋放音訊取樣緩衝區 swr_free(&swrCtx);//釋放音訊取樣上下文 //關閉PCM裝置 snd_pcm_drain(handle); snd_pcm_close(handle); av_frame_free(&audioFrame);//釋放audioFrame av_frame_free(&videoFrame);//釋放videoFrame av_packet_free(&avPacket);//釋放avPacket avcodec_close(videoCodecContext);//關閉音訊解碼器 avcodec_close(audioCodecContext);//關閉視訊解碼器 avformat_close_input(&avFormatContext);//關閉輸入檔案 return 0; } int main() { ffmpeg_decode(); }
這個例子使用qt creator寫的，需要連結動態庫什麼的
//連結alsa庫 LIBS += -lasound //加入ffmpeg標頭檔案並連結ffmpeg庫 INCLUDEPATH += /usr/local/ffmpeg/include LIBS += -L/usr/local/ffmpeg/lib/ -lswscale -lswresample -lavutil -lavformat -lavfilter -lavdevice -lavcodec //加入opencv標頭檔案並連結opencv庫 INCLUDEPATH += /usr/local/include LIBS += -L/usr/local/lib/ -lopencv_calib3d -lopencv_core -lopencv_features2d -lopencv_flann -lopencv_highgui -lopencv_imgcodecs -lopencv_imgproc -lopencv_ml -lopencv_objdetect -lopencv_photo -lopencv_shape -lopencv_stitching -lopencv_superres -lopencv_videoio -lopencv_video -lopencv_videostab
遇到的問題：
剛開始不知道怎麼播放音訊，所以就學了一下如何使用alsa播放pcm音訊資料，找了一個pcm檔案，用來測試alsa的程式碼是否正確。
後來用ffmpeg解碼wav格式的資料，再用alsa播放音訊發現可以正常播放，就直接拿視訊檔案來測試，使用ffmpeg解碼視訊檔案後，發現音訊播放時一直出現雜音不正常，後來才知道從視訊檔案解碼後的音訊流格式與設定alsa播放的格式不一樣，需要對解碼後的音訊資料進行重新取樣，然後再送到音效卡裝置播放，這樣就能正常播放了。