標籤:oid setbuf lib 清單 effort sizeof stride [] pos
項目地址,求star
https://github.com/979451341/Audio-and-video-learning-materials/tree/master/FFmpeg(AVfilter%E8%BF%87%E6%BB%A4%EF%BC%89
1.AVfilter結構體成員
這個特效要靠AVfilter來實現,首先說一下說AVfilter這個結構體的成員
/
*過濾器定義。這定義了一個過濾器包含的墊,以及所有的
*用於與篩選器互動的回呼函數。
- /
typedef struct AVFilter {
/
*過濾器名稱。在過濾器中必須是非空且唯一的。
/
*描述濾波器。可能是空的。
*
你應該使用null_if_config_small()宏定義。
/
const char *description;
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*輸入清單,由零元終止。
*
*如果沒有(靜態)輸入,則為null。過濾器執行個體
- avfilter_flag_dynamic_inputs集可能會有比現在更多的投入
*這份清單。
/
*輸出清單,由零元終止。
*
*如果沒有(靜態)輸出,則為null。過濾器執行個體
- avfilter_flag_dynamic_outputs集可能會有比現在更多的產出
*這份清單。
/
*一個私人資料的類,用於聲明私人avoptions過濾器。
*此欄位對於未聲明任何選項的篩選器無效。
*
*如果該欄位非空,則是篩選私人資料的第一個成員。
*必須是指標對avclass,這將由libavfilter通用
*這個類的代碼。
/
結合avfilterflag
2.AVfilter使用步驟
現在直接在代碼上說這個AVfilter使用的步驟
因為使用濾鏡,所以需要播放視頻,就要解碼,來段標準準備代碼
// sd卡中的視頻檔案地址,可自行修改或者通過jni傳入char *file_name = "/storage/emulated/0/pauseRecordDemo/video/2018-02-03-09-25-34.mp4";//char *file_name = "/storage/emulated/0/video.avi";av_register_all();
//註冊所有AVFilter。
avfilter_register_all();//added by ws for AVfilter
AVFormatContext *pFormatCtx = avformat_alloc_context();// Open video fileif (avformat_open_input(&pFormatCtx, file_name, NULL, NULL) != 0) { LOGD("Couldn‘t open file:%s\n", file_name); return -1; // Couldn‘t open file}// Retrieve stream informationif (avformat_find_stream_info(pFormatCtx, NULL) < 0) { LOGD("Couldn‘t find stream information."); return -1;}// Find the first video streamint videoStream = -1, i;for (i = 0; i < pFormatCtx->nb_streams; i++) { if (pFormatCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO && videoStream < 0) { videoStream = i; }}if (videoStream == -1) { LOGD("Didn‘t find a video stream."); return -1; // Didn‘t find a video stream}// Get a pointer to the codec context for the video streamAVCodecContext *pCodecCtx = pFormatCtx->streams[videoStream]->codec;
開始濾鏡的準備
AVFilter *buffersrc = avfilter_get_by_name("buffer");AVFilter *buffersink = avfilter_get_by_name("buffersink");//新版的ffmpeg庫必須為buffersinkAVFilterInOut *outputs = avfilter_inout_alloc();AVFilterInOut *inputs = avfilter_inout_alloc();enum AVPixelFormat pix_fmts[] = { AV_PIX_FMT_YUV420P, AV_PIX_FMT_NONE };AVBufferSinkParams *buffersink_params;
//為FilterGraph分配記憶體。
filter_graph = avfilter_graph_alloc();
//建立並向FilterGraph中添加一個Filter。
ret = avfilter_graph_create_filter(&buffersrc_ctx, buffersrc, "in",
args, NULL, filter_graph);
if (ret < 0) {
LOGD("Cannot create buffer source\n");
return ret;
}
buffersink_params = av_buffersink_params_alloc();buffersink_params->pixel_fmts = pix_fmts;
//建立並向FilterGraph中添加一個Filter。
ret = avfilter_graph_create_filter(&buffersink_ctx, buffersink, "out",
NULL, buffersink_params, filter_graph);
av_free(buffersink_params);
if (ret < 0) {
LOGD("Cannot create buffer sink\n");
return ret;
}
給AVfilter的輸入輸出描述賦值
outputs->name = av_strdup("in");outputs->filter_ctx = buffersrc_ctx;outputs->pad_idx = 0;outputs->next = NULL;inputs->name = av_strdup("out");inputs->filter_ctx = buffersink_ctx;inputs->pad_idx = 0;inputs->next = NULL;
配置和使用濾鏡效果,改變u、v這個兩個像素,使畫面顯示黑白
const char *filters_descr = "lutyuv=‘u=128:v=128‘";
//將一串通過字串描述的Graph添加到FilterGraph中。
if ((ret = avfilter_graph_parse_ptr(filter_graph, filters_descr,
&inputs, &outputs, NULL)) < 0) {
LOGD("Cannot avfilter_graph_parse_ptr\n");
return ret;
}
//檢查FilterGraph的配置。
if ((ret = avfilter_graph_config(filter_graph, NULL)) < 0) {
LOGD("Cannot avfilter_graph_config\n");
return ret;
}
接下來就是渲染
// Find the decoder for the video streamAVCodec *pCodec = avcodec_find_decoder(pCodecCtx->codec_id);if (pCodec == NULL) { LOGD("Codec not found."); return -1; // Codec not found}if (avcodec_open2(pCodecCtx, pCodec, NULL) < 0) { LOGD("Could not open codec."); return -1; // Could not open codec}// 擷取native windowANativeWindow *nativeWindow = ANativeWindow_fromSurface(env, surface);// 擷取視頻寬高int videoWidth = pCodecCtx->width;int videoHeight = pCodecCtx->height;// 設定native window的buffer大小,可自動展開ANativeWindow_setBuffersGeometry(nativeWindow, videoWidth, videoHeight, WINDOW_FORMAT_RGBA_8888);ANativeWindow_Buffer windowBuffer;if (avcodec_open2(pCodecCtx, pCodec, NULL) < 0) { LOGD("Could not open codec."); return -1; // Could not open codec}// Allocate video frameAVFrame *pFrame = av_frame_alloc();// 用於渲染AVFrame *pFrameRGBA = av_frame_alloc();if (pFrameRGBA == NULL || pFrame == NULL) { LOGD("Could not allocate video frame."); return -1;}// Determine required buffer size and allocate buffer// buffer中資料就是用於渲染的,且格式為RGBAint numBytes = av_image_get_buffer_size(AV_PIX_FMT_RGBA, pCodecCtx->width, pCodecCtx->height, 1);uint8_t *buffer = (uint8_t *) av_malloc(numBytes * sizeof(uint8_t));av_image_fill_arrays(pFrameRGBA->data, pFrameRGBA->linesize, buffer, AV_PIX_FMT_RGBA, pCodecCtx->width, pCodecCtx->height, 1);// 由於解碼出來的框架格式不是RGBA的,在渲染之前需要進行格式轉換struct SwsContext *sws_ctx = sws_getContext(pCodecCtx->width, pCodecCtx->height, pCodecCtx->pix_fmt, pCodecCtx->width, pCodecCtx->height, AV_PIX_FMT_RGBA, SWS_BILINEAR, NULL, NULL, NULL);
解碼和釋放資源,在解碼的時候將解碼的資料放入FilterGraph去顯示
while (av_read_frame(pFormatCtx, &packet) >= 0) { // Is this a packet from the video stream? if (packet.stream_index == videoStream) { // Decode video frame avcodec_decode_video2(pCodecCtx, pFrame, &frameFinished, &packet); // 並不是decode一次就可解碼出一幀 if (frameFinished) { //added by ws for AVfilter start pFrame->pts = av_frame_get_best_effort_timestamp(pFrame); //* 向FilterGraph中加入一個AVFrame。 if (av_buffersrc_add_frame(buffersrc_ctx, pFrame) < 0) { LOGD("Could not av_buffersrc_add_frame"); break; }
//從FilterGraph中取出一個AVFrame。
ret = av_buffersink_get_frame(buffersink_ctx, pFrame);
if (ret < 0) {
LOGD("Could not av_buffersink_get_frame");
break;
}
//added by ws for AVfilter end
// lock native window buffer ANativeWindow_lock(nativeWindow, &windowBuffer, 0); // 格式轉換 sws_scale(sws_ctx, (uint8_t const *const *) pFrame->data, pFrame->linesize, 0, pCodecCtx->height, pFrameRGBA->data, pFrameRGBA->linesize); // 擷取stride uint8_t *dst = (uint8_t *) windowBuffer.bits; int dstStride = windowBuffer.stride * 4; uint8_t *src = (pFrameRGBA->data[0]); int srcStride = pFrameRGBA->linesize[0]; // 由於window的stride和幀的stride不同,因此需要逐行複製 int h; for (h = 0; h < videoHeight; h++) { memcpy(dst + h * dstStride, src + h * srcStride, srcStride); } ANativeWindow_unlockAndPost(nativeWindow); } } av_packet_unref(&packet);}av_free(buffer);av_free(pFrameRGBA);// Free the YUV frameav_free(pFrame);avfilter_graph_free(&filter_graph); //added by ws for avfilter// Close the codecsavcodec_close(pCodecCtx);
這個想要真正掌握,需要將avfilter.c至少過個兩個遍,因為這下面四個結構體還沒有看看他們的內部成員
typedef struct AVFilterContext AVFilterContext;
typedef struct AVFilterLink AVFilterLink;
typedef struct AVFilterPad AVFilterPad;
typedef struct AVFilterFormats AVFilterFormats;
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