之前在https://blog.csdn.net/fengbingchun/article/details/103444891中介绍过在Windows上通过ffmpeg dshow设置为mjpeg编解码方式进行实时显示的测试代码。这里测试仅调用ffmpeg的mjpeg编码接口，获取到packet后，通过libyuv+libjpeg-turbo对mjpeg进行解码并实时显示的测试代码，代码如下：
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#include <stdio.h>
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#include <string.h>
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#include <iostream>
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#include <memory>
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#ifdef __cplusplus
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extern
"C" {
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#endif
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#include <libavdevice/avdevice.h>
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#include <libavformat/avformat.h>
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#include <libavcodec/avcodec.h>
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#include <libswscale/swscale.h>
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#include <libavutil/mem.h>
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#include <libavutil/imgutils.h>
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#ifdef __cplusplus
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}
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#endif
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#include <opencv2/opencv.hpp>
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#include <libyuv/convert_argb.h>
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#include <libyuv/convert.h>
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int test_ffmpeg_dshow_mjpeg_encode_libyuv_decode()
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{
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avdevice_register_all();
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AVCodecID id = AV_CODEC_ID_MJPEG;
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AVCodec* encoder_id = avcodec_find_encoder(id);
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if (!encoder_id) {
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fprintf(
stderr,
"codec not found: %d\n", id);
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return
-1;
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}
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AVFormatContext* format_context = avformat_alloc_context();
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format_context->video_codec_id = id;
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AVInputFormat* input_format = av_find_input_format(
"dshow");
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AVDictionary* dict =
nullptr;
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if (av_dict_set(&dict,
"video_size",
"960x540",
0) <
0)
fprintf(
stderr,
"fail to av_dict_set: line: %d\n", __LINE__);
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int ret = avformat_open_input(&format_context,
"video=Integrated Webcam", input_format, &dict);
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if (ret !=
0) {
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fprintf(
stderr,
"fail to avformat_open_input: %d\n", ret);
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return
-1;
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}
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ret = avformat_find_stream_info(format_context,
nullptr);
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if (ret <
0) {
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fprintf(
stderr,
"fail to get stream information: %d\n", ret);
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return
-1;
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}
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int video_stream_index =
-1;
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for (
unsigned
int i =
0; i < format_context->nb_streams; ++i) {
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const AVStream* stream = format_context->streams[i];
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if (stream->codecpar->codec_type == AVMEDIA_TYPE_VIDEO) {
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video_stream_index = i;
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fprintf(
stdout,
"type of the encoded data: %d, dimensions of the video frame in pixels: width: %d, height: %d, pixel format: %d\n",
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stream->codecpar->codec_id, stream->codecpar->width, stream->codecpar->height, stream->codecpar->format);
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}
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}
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if (video_stream_index ==
-1) {
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fprintf(
stderr,
"no video stream\n");
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return
-1;
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}
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AVCodecParameters* codecpar = format_context->streams[video_stream_index]->codecpar;
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if (codecpar->codec_id != id) {
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fprintf(
stderr,
"this test code only support mjpeg encode: %d\n", codecpar->codec_id);
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return
-1;
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}
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AVPacket* packet = (AVPacket*)av_malloc(
sizeof(AVPacket));
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if (!packet) {
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fprintf(
stderr,
"fail to alloc\n");
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return
-1;
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}
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std::
unique_ptr<
unsigned
char[]> data(
new
unsigned
char[codecpar->width * codecpar->height *
4]);
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cv::
Mat mat(codecpar->height,codecpar->width, CV_8UC4, data.get());
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const
char* winname =
"dshow mjpeg encode and libyuv decode";
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cv::namedWindow(winname);
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AVFrame* frame = av_frame_alloc();
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while (
1) {
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ret = av_read_frame(format_context, packet);
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if (ret >=
0 && packet->stream_index == video_stream_index && packet->size >
0) {
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int dst_width, dst_height;
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libyuv::MJPGSize(packet->data, packet->size, &dst_width, &dst_height);
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if (dst_width != codecpar->width || dst_height != codecpar->height) {
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fprintf(
stderr,
"width or height dismatch: (%d, %d), (%d, %d)\n",
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dst_width, dst_height, codecpar->width, codecpar->height);
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return
-1;
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}
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libyuv::MJPGToARGB(packet->data, packet->size, data.get(), dst_width *
4,
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codecpar->width, codecpar->height, dst_width, dst_height);
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cv::imshow(winname, mat);
-
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}
else
if (ret <
0 || packet->size <=
0) {
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fprintf(
stderr,
"fail to av_read_frame: %d, packet size: %d\n", ret, packet->size);
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continue;
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}
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av_packet_unref(packet);
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int key = cv::waitKey(
30);
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if (key ==
27)
break;
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}
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cv::destroyWindow(winname);
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av_freep(packet);
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avformat_close_input(&format_context);
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av_dict_free(&dict);
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fprintf(
stdout,
"test finish\n");
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return
0;
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}
执行结果如下：
GitHub：https://github.com//fengbingchun/OpenCV_Test
转载：https://blog.csdn.net/fengbingchun/article/details/103583548
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