Libav AVFrame to Opencv Mat to AVPacket conversion
Libav AVFrame to Opencv Mat to AVPacket conversion
我是libav的新手，我正在编写一个以opencv为核心的视频处理软件。我所做的简要如下：
1-读取视频包
2-将数据包解码为AVFrame。
3-转换 AVFrame到CV垫
4-操纵垫子
5-转换简历垫 成AVFrame中
6-将AVFrame编码为AVPacket
7-写入数据包
8-转到1
我在 http://dranger.com/ffmpeg/tutorial01.html 中阅读了 dranger 教程，我也使用了decoding_encoding示例。我可以阅读视频，提取视频帧并将其转换为CV Mat。我的问题从从cv Mat转换为AVFrame并将其编码为AVPacket开始。
你能帮我这个吗？
这是我的代码：
int main(int argc, char **argv)
{
AVOutputFormat *ofmt = NULL;
AVFormatContext *ifmt_ctx = NULL, *ofmt_ctx = NULL;
AVPacket pkt;
AVCodecContext *pCodecCtx = NULL;
AVCodec *pCodec = NULL;
AVFrame *pFrame = NULL;
AVFrame *pFrameRGB = NULL;
int videoStream=-1;
int audioStream=-1;
int frameFinished;
int numBytes;
uint8_t *buffer = NULL;
struct SwsContext *sws_ctx = NULL;
FrameManipulation *mal_frame;
const char *in_filename, *out_filename;
int ret, i;
if (argc < 3) {
printf("usage: %s input outputn"
"API example program to remux a media file with libavformat and libavcodec.n"
"The output format is guessed according to the file extension.n"
"n", argv[0]);
return 1;
}
in_filename = arg[1];
out_filename = arg[2];
av_register_all();
if ((ret = avformat_open_input(&ifmt_ctx, in_filename, 0, 0)) < 0) {
fprintf(stderr, "Could not open input file '%s'", in_filename);
goto end;
}
if ((ret = avformat_find_stream_info(ifmt_ctx, 0)) < 0) {
fprintf(stderr, "Failed to retrieve input stream information");
goto end;
}
av_dump_format(ifmt_ctx, 0, in_filename, 0);
avformat_alloc_output_context2(&ofmt_ctx, NULL, NULL, out_filename);
if (!ofmt_ctx) {
fprintf(stderr, "Could not create output contextn");
ret = AVERROR_UNKNOWN;
goto end;
}
ofmt = ofmt_ctx->oformat;
for (i = 0; i < ifmt_ctx->nb_streams; i++) {
AVStream *in_stream = ifmt_ctx->streams[i];
AVStream *out_stream = avformat_new_stream(ofmt_ctx, in_stream->codec->codec);
if(ifmt_ctx->streams[i]->codec->codec_type==AVMEDIA_TYPE_VIDEO &&
videoStream < 0) {
videoStream=i;
}
if(ifmt_ctx->streams[i]->codec->codec_type==AVMEDIA_TYPE_AUDIO &&
audioStream < 0) {
audioStream=i;
}
if (!out_stream) {
fprintf(stderr, "Failed allocating output streamn");
ret = AVERROR_UNKNOWN;
goto end;
}
ret = avcodec_copy_context(out_stream->codec, in_stream->codec);
if (ret < 0) {
fprintf(stderr, "Failed to copy context from input to output stream codec contextn");
goto end;
}
out_stream->codec->codec_tag = 0;
if (ofmt_ctx->oformat->flags & AVFMT_GLOBALHEADER)
out_stream->codec->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;
}
pCodec=avcodec_find_decoder(ifmt_ctx->streams[videoStream]->codec->codec_id);
pCodecCtx = avcodec_alloc_context3(pCodec);
if(avcodec_copy_context(pCodecCtx, ifmt_ctx->streams[videoStream]->codec) != 0) {
fprintf(stderr, "Couldn't copy codec context");
return -1; // Error copying codec context
}
// Open codec
if(avcodec_open2(pCodecCtx, pCodec, NULL)<0)
return -1; // Could not open codec
// Allocate video frame
pFrame=av_frame_alloc();
// Allocate an AVFrame structure
pFrameRGB=av_frame_alloc();
// Determine required buffer size and allocate buffer
numBytes=avpicture_get_size(AV_PIX_FMT_RGB24, ifmt_ctx->streams[videoStream]->codec->width,
ifmt_ctx->streams[videoStream]->codec->height);
buffer=(uint8_t *)av_malloc(numBytes*sizeof(uint8_t));
// Assign appropriate parts of buffer to image planes in pFrameRGB
// Note that pFrameRGB is an AVFrame, but AVFrame is a superset
// of AVPicture
avpicture_fill((AVPicture *)pFrameRGB, buffer, AV_PIX_FMT_BGR24,
ifmt_ctx->streams[videoStream]->codec->width, ifmt_ctx->streams[videoStream]->codec->height);
av_dump_format(ofmt_ctx, 0, out_filename, 1);
if (!(ofmt->flags & AVFMT_NOFILE)) {
ret = avio_open(&ofmt_ctx->pb, out_filename, AVIO_FLAG_WRITE);
if (ret < 0) {
fprintf(stderr, "Could not open output file '%s'", out_filename);
goto end;
}
}
ret = avformat_write_header(ofmt_ctx, NULL);
if (ret < 0) {
fprintf(stderr, "Error occurred when opening output filen");
goto end;
}
// Assign appropriate parts of buffer to image planes in pFrameRGB
// Note that pFrameRGB is an AVFrame, but AVFrame is a superset
// of AVPicture
avpicture_fill((AVPicture *)pFrameRGB, buffer, AV_PIX_FMT_BGR24,
ifmt_ctx->streams[videoStream]->codec->width,
ifmt_ctx->streams[videoStream]->codec->height);
// initialize SWS context for software scaling
sws_ctx = sws_getContext(
ifmt_ctx->streams[videoStream]->codec->width,
ifmt_ctx->streams[videoStream]->codec->height,
ifmt_ctx->streams[videoStream]->codec->pix_fmt,
ifmt_ctx->streams[videoStream]->codec->width,
ifmt_ctx->streams[videoStream]->codec->height,
AV_PIX_FMT_BGR24,
SWS_BICUBIC,
NULL,
NULL,
NULL
);
// Loop through packets
while (1) {
AVStream *in_stream, *out_stream;
ret = av_read_frame(ifmt_ctx, &pkt);
if(pkt.stream_index==videoStream)
// Decode video frame
avcodec_decode_video2(pCodecCtx, pFrame, &frameFinished, &pkt);
if(frameFinished) {
sws_scale(sws_ctx, (uint8_t const * const *)pFrame->data,
pFrame->linesize, 0, pCodecCtx->height,
pFrameRGB->data, pFrameRGB->linesize);
cv::Mat img= mal_frame->process(
pFrameRGB,pFrame->width,pFrame->height);
/* My problem is Here ------------*/
avpicture_fill((AVPicture*)pFrameRGB,
img.data,
PIX_FMT_BGR24,
outStream->codec->width,
outStream->codec->height);
pFrameRGB->width = ifmt_ctx->streams[videoStream]->codec->width;
pFrameRGB->height = ifmt_ctx->streams[videoStream]->codec->height;
avcodec_encode_video2(ifmt_ctx->streams[videoStream]->codec ,
&pkt , pFrameRGB , &gotPacket);
/*
I get this error
[swscaler @ 0x14b58a0] bad src image pointers
[swscaler @ 0x14b58a0] bad src image pointers
*/
/* My Problem Ends here ---------- */
}
if (ret < 0)
break;
in_stream = ifmt_ctx->streams[pkt.stream_index];
out_stream = ofmt_ctx->streams[pkt.stream_index];
//log_packet(ifmt_ctx, &pkt, "in");
/* copy packet */
pkt.pts = av_rescale_q_rnd(pkt.pts, in_stream->time_base, out_stream->time_base,
AV_ROUND_NEAR_INF);
pkt.dts = av_rescale_q_rnd(pkt.dts, in_stream->time_base, out_stream->time_base, AV_ROUND_NEAR_INF);
pkt.duration = av_rescale_q(pkt.duration, in_stream->time_base, out_stream->time_base);
pkt.pos = -1;
log_packet(ofmt_ctx, &pkt, "out");
ret = av_interleaved_write_frame(ofmt_ctx, &pkt);
if (ret < 0) {
fprintf(stderr, "Error muxing packetn");
break;
}
av_free_packet(&pkt);
}
av_write_trailer(ofmt_ctx);
end:
avformat_close_input(&ifmt_ctx);
/* close output */
if (ofmt_ctx && !(ofmt->flags & AVFMT_NOFILE))
avio_closep(&ofmt_ctx->pb);
avformat_free_context(ofmt_ctx);
if (ret < 0 && ret != AVERROR_EOF) {
return 1;
}
return 0;
}
当我运行此代码时，我在此部分中遇到未知的致命错误：
/* My problem is Here ------------*/
avpicture_fill((AVPicture*)pFrameRGB,
img.data,
PIX_FMT_BGR24,
outStream->codec->width,
outStream->codec->height);
pFrameRGB->width = ifmt_ctx->streams[videoStream]->codec->width;
pFrameRGB->height = ifmt_ctx->streams[videoStream]->codec->height;
avcodec_encode_video2(ifmt_ctx->streams[videoStream]->codec ,
&pkt , pFrameRGB , &gotPacket);
/*
I get this error
[swscaler @ 0x14b58a0] bad src image pointers
[swscaler @ 0x14b58a0] bad src image pointers
*/
/* My Problem Ends here ---------- */
在这里，我想将cv Mat转换回AVFrame并将其编码为AVPacket。我感谢您的帮助。
在阅读了一些示例，阅读了源代码和一些帮助人们之后，我设法使代码运行。我使用了转码和编码示例并将它们混合在一起。这是我的代码
以下是亮点： 1- libswscale应该用于转换AVFrame，需要将所需的数据包格式输入到openCV Mat中。为此，我们定义
struct SwsContext *sws_ctx = NULL;
sws_ctx = sws_getContext(pCodecCtx->width,
pCodecCtx->height,
pCodecCtx->pix_fmt,
pCodecCtx->width,
pCodecCtx->height,
AV_PIX_FMT_BGR24,
SWS_BICUBIC,
NULL,
NULL,
NULL
);
要将opencv Mat转换回AVFrame，应再次使用swscale并将opencv BGR帧格式转换为YUV格式。所以，我这样做：
struct SwsContext *sws_ctx_bgr_yuv = NULL;
sws_ctx_bgr_yuv = sws_getContext(pCodecCtx->width,
pCodecCtx->height,
AV_PIX_FMT_BGR24,
pCodecCtx->width,
pCodecCtx->height,
pCodecCtx->pix_fmt //AV_PIX_FMT_YUV420p
,0,0,NULL,NULL);
而且，这是帧读取/解码/编码循环：
while (1) {
if ((ret = av_read_frame(ifmt_ctx, &packet)) < 0)
break;
stream_index = packet.stream_index;
type = ifmt_ctx->streams[packet.stream_index]->codec->codec_type;
av_log(NULL, AV_LOG_DEBUG, "Demuxer gave frame of stream_index %un",
stream_index);
if (filter_ctx[stream_index].filter_graph) {
av_log(NULL, AV_LOG_DEBUG, "Going to reencode&filter the framen");
frame = av_frame_alloc();
if (!frame) {
ret = AVERROR(ENOMEM);
break;
}
av_packet_rescale_ts(&packet,
ifmt_ctx->streams[stream_index]->time_base,
ifmt_ctx->streams[stream_index]->codec->time_base);
dec_func = (type == AVMEDIA_TYPE_VIDEO) ? avcodec_decode_video2 :
avcodec_decode_audio4;
ret = dec_func(ifmt_ctx->streams[stream_index]->codec, frame,
&got_frame, &packet);
if (ret < 0) {
av_frame_free(&frame);
av_log(NULL, AV_LOG_ERROR, "Decoding failedn");
break;
}
if (got_frame) {
if(stream_index==video_index){
sws_scale(sws_ctx, (uint8_t const * const *)frame->data,
frame->linesize, 0, pCodecCtx->height,
pFrameRGB->data, pFrameRGB->linesize);
/*------------------------------------------------------------------------
/* Frame converts to opencv Mat
/*------------------------------------------------------------------------*/
cv::Mat img(frame->height,frame->width,CV_8UC3,pFrameRGB->data[0]);
img=manipulate_image(img); //this is opencv Mat, do whatever you want, but don't change its dimensions and format
//manipulate_function can be considered as as simple as blurring
const int stride[] = {img.step[0] };
/* opencv Mat converts back to AVFrame */
sws_scale(sws_ctx_bgr_yuv, &img.data, stride, 0, img.rows, frame->data, frame->linesize);
}
frame->pts = av_frame_get_best_effort_timestamp(frame);
/* AVFrame re-encodes to AVPacket and will be sent to encoder */
ret = filter_encode_write_frame(frame, stream_index);
av_frame_free(&frame);
if (ret < 0)
goto end;
} else {
av_frame_free(&frame);
}
} else {
/* remux this frame without reencoding */
av_packet_rescale_ts(&packet,
ifmt_ctx->streams[stream_index]->time_base,
ofmt_ctx->streams[stream_index]->time_base);
ret = av_interleaved_write_frame(ofmt_ctx, &packet);
if (ret < 0)
goto end;
}
av_free_packet(&packet);
}
这是另一种使用 c++ 在 cv::Mat 和 AVframe 之间进行转换的方法，基于我找到和调试的一些代码。请注意，它专门用于 8 位 3 通道图像，但可以通过更改两个功能中的AV_PIX_FMT_BGR24来更改。
希望这有帮助。
AVFrame cvmat_to_avframe(cv::Mat* frame)
{
AVFrame dst;
cv::Size frameSize = frame->size();
AVCodec *encoder = avcodec_find_encoder(AV_CODEC_ID_RAWVIDEO);
AVFormatContext* outContainer = avformat_alloc_context();
AVStream *outStream = avformat_new_stream(outContainer, encoder);
avcodec_get_context_defaults3(outStream->codec, encoder);
outStream->codec->pix_fmt = AV_PIX_FMT_BGR24;
outStream->codec->width = frame->cols;
outStream->codec->height = frame->rows;
avpicture_fill((AVPicture*)&dst, frame->data, AV_PIX_FMT_BGR24, outStream->codec->width, outStream->codec->height);
dst.width = frameSize.width;
dst.height = frameSize.height;
return dst;
}
cv::Mat avframe_to_cvmat(AVFrame *frame)
{
AVFrame dst;
cv::Mat m;
memset(&dst, 0, sizeof(dst));
int w = frame->width, h = frame->height;
m = cv::Mat(h, w, CV_8UC3);
dst.data[0] = (uint8_t *)m.data;
avpicture_fill( (AVPicture *)&dst, dst.data[0], AV_PIX_FMT_BGR24, w, h);
struct SwsContext *convert_ctx=NULL;
enum AVPixelFormat src_pixfmt = AV_PIX_FMT_BGR24;
enum AVPixelFormat dst_pixfmt = AV_PIX_FMT_BGR24;
convert_ctx = sws_getContext(w, h, src_pixfmt, w, h, dst_pixfmt,
SWS_FAST_BILINEAR, NULL, NULL, NULL);
sws_scale(convert_ctx, frame->data, frame->linesize, 0, h,
dst.data, dst.linesize);
sws_freeContext(convert_ctx);
return m;
}
相关文章：
- "error: no matching function for call to"构造函数错误
- 调用专用模板时出错"no matching function for call to [...]"
- C++ Singleton - Prevent ::instance() to variable
- 我的项目不会像"undefined reference to `grpc::g_core_codegen_interface'"那样使用未定义的引用错误进行编译
- Visual Studio Code "undefined reference to `WinMain@16'"
- 使用 GCC 卸载的 OpenMP 卸载失败，并出现"Ptx assembly aborted due to errors"
- 如何解决"invalid conversion from 'char' to 'const char*'"
- 使用 MATLAB 编码器生成C++代码：编译错误"undefined reference to `rgb2gray_tbb_real64'"
- 尝试链接我的着色器时，我收到错误代码"error c5145 must write to gl_position"
- Python str to C++ to Python str
- 为什么创建友元类的实例会导致"undefined reference to"错误？
- System.InvalidCastException - SQL to C++ - safe_cast<float>
- 使用 cmake 的 Linux 终端上的"Conversion to non-scalar type is requested"错误
- "no matching function for call to 'Vector::Vector'"错误
- vector<vector<double>> to mxArray using memcpy
- Tensorflow c++ api undefined reference to 'tflite：:D efaultErrorReporter()'
- 当覆盖存在时调用基本虚拟"binded to object"函数
- OpenGL VBO Indexing ( How to compute Index Array)
- 为什么我会" void value not ignored as it ought to be"？
- Libav AVFrame to Opencv Mat to AVPacket conversion
