Android 音視頻深入 十 FFmpeg給視頻加特效(附源碼下載)
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
*用於與篩選器交互的回調函數。
- /
typedef struct AVFilter {
/
*過濾器名稱。在過濾器中必須是非空且唯一的。
-
/
const char *name;
/
*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;
/
*輸入清單,由零元終止。
*
*如果沒有(靜態)輸入,則為null。過濾器實例
- avfilter_flag_dynamic_inputs集可能會有比現在更多的投入
*這份清單。
-
/
const AVFilterPad *inputs;
/
*輸出清單,由零元終止。
*
*如果沒有(靜態)輸出,則為null。過濾器實例
- avfilter_flag_dynamic_outputs集可能會有比現在更多的產出
*這份清單。
-
/
const AVFilterPad *outputs;
/
*一個私人數據的類,用於聲明私人avoptions過濾器。
*此字段對於未聲明任何選項的篩選器無效。
*
*如果該字段非空,則是篩選私有數據的第一個成員。
*必須是指針對avclass,這將由libavfilter通用
*這個類的代碼。
-
/
const AVClass *priv_class;
/
結合avfilterflag
-
/
int flags;
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卡中的視頻文件地址,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 file
if (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 information
if (avformat_find_stream_info(pFormatCtx, NULL) < 0) {
LOGD("Couldn‘t find stream information.");
return -1;
}
// Find the first video stream
int 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 stream
AVCodecContext *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buffersink
AVFilterInOut *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分配內存。
filter_graph = avfilter_graph_alloc();
//創建並向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;
//創建並向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‘";
//將一串通過字符串描述的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 stream
AVCodec *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
}
// 獲取native window
ANativeWindow *nativeWindow = ANativeWindow_fromSurface(env, surface);
// 獲取視頻寬高
int videoWidth = pCodecCtx->width;
int videoHeight = pCodecCtx->height;
// 設置native window的buffer大小,可自動拉伸
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 frame
AVFrame *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中數據就是用於渲染的,且格式為RGBA
int 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);
// 由於解碼出來的幀格式不是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數據放入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);
// 獲取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,因此需要逐行復制
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 frame
av_free(pFrame);
avfilter_graph_free(&filter_graph); //added by ws for avfilter
// Close the codecs
avcodec_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;
Android 音視頻深入 十 FFmpeg給視頻加特效(附源碼下載)