关于开发库的版本问题
ffmpeg抽取视频中motion vector的小结，
代码出自这个网页。使用Zeranoe FFmpeg编译的库，也可以使用自己vs2010编译。
建立工程
- 建立空白win32 console app
- 新建C++文件，添加代码
- $(ProjectDir)\ffmpegSDK\lib目录下创建目录ffmpegSDK，解压ffmpeg-2.0.1-win32-dev.7z中的include、lib到ffmpegSDK。
- C/C++-->常规-->附加包含目录，添加$(ProjectDir)\ffmpegSDK\include;
- 链接库-->常规-->附加库目录，添加$(ProjectDir)\ffmpegSDK\lib;
- 链接库-->输入-->附加依赖项，
添加ws2_32.lib;avcodec.lib;avdevice.lib;avfilter.lib;avformat.lib;avutil.lib;postproc.lib;swresample.lib;swscale.lib;
编译工程
可见有很多错误，其中需要修改的是：
- 注释掉
<![CDATA[
#include <stdbool.h>
]]>
- 添加extern "C"相关
- FF_P_TYPE等改为AV_PICTURE_TYPE_P
- av_open_input_file(&pFormatCtx, argv[1], NULL, 0, NULL)改为
avformat_open_input(&pFormatCtx, argv[1], NULL, NULL)
- dump_format(pFormatCtx, 0, argv[1], false)改为
av_dump_format(pFormatCtx, 0, argv[1], false)
- CODEC_TYPE_VIDEO改为AVMEDIA_TYPE_VIDEO
- avcodec_decode_video(pCodecCtx, pFrame, &frameFinished, packet.data, packet.size)改为
avcodec_decode_video2(pCodecCtx, pFrame, &frameFinished, &packet)
开始调试
- 生成成功之后，添加调试参数rtsp://192.168.1.158/H264,开始调试提示缺少dll文件，需要下载相应dev版本的share版本并解压到工程的Debug目录。
- 调试总是在if(avformat_open_input(&pFormatCtx, argv[1], NULL, NULL)!=0)位置中断，由于版本升级需要把pFormatCtx初始化为NULL，好蛋疼的版本升级。
- 程序运行，但是控制台提示：Using network protocols without global network initialization. Please use avform at_network_init(), this will become mandatory later.需要添加avformat_network_init()到av_register_all();之后。
- 总是在if (!USES_LIST(pict->mb_type[mb_index], direction))这个地方中断，网上找了几天的原因也没解决，主要的思路就是
pCodecCtx->debug |= FF_DEBUG_MV | FF_DEBUG_MB_TYPE;
pCodecCtx->debug_mv |= FF_DEBUG_VIS_MV_P_FOR | FF_DEBUG_VIS_MV_B_FOR | FF_DEBUG_VIS_MV_B_BACK;但是同样的问题，不过确实出现了visual motion vector，但是还是中断在那个位置，无奈之下，更换了ffmpeg-1.2-win32-dev这个版本之后，问题解决了。版本升级伤不起啊，开始还以为编译的时候出了问题，现在的看法是，新版本即使添加FF_DEBUG_MV，但avframe.mb_type还是不会被填充，遇到类似问题需要注意。
最后附上修改过的代码
<![CDATA[
extern "C"{
#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>
#include <libswscale/swscale.h>
}
#include <stdio.h>
#include <stdlib.h>
//#include <stdbool.h>
#define IS_INTERLACED(a) ((a)&MB_TYPE_INTERLACED)
#define IS_16X16(a) ((a)&MB_TYPE_16x16)
#define IS_16X8(a) ((a)&MB_TYPE_16x8)
#define IS_8X16(a) ((a)&MB_TYPE_8x16)
#define IS_8X8(a) ((a)&MB_TYPE_8x8)
#define USES_LIST(a, list) ((a) & ((MB_TYPE_P0L0|MB_TYPE_P1L0)<<(2*(list))))
static void SaveFrame(AVFrame *pFrame, int width, int height, int iFrame)
{
FILE *pFile;
char szFilename[32];
int y;
// Open file
sprintf(szFilename, "frame%d.ppm", iFrame);
printf("Open File: frame%d.ppm\n", iFrame);
pFile=fopen(szFilename, "wb");
if(pFile==NULL)
return;
// Write header
fprintf(pFile, "P6\n%d %d\n255\n", width, height);
// Write pixel data
for(y=0; y<height; y++)
fwrite(pFrame->data[0]+y*pFrame->linesize[0], 1, width*3, pFile);
// Close file
fclose(pFile);
}
void SavePGM(AVFrame *pFrame, int width, int height, int iFrame)
{
FILE *fp =0;
int i,j,shift;
uint8_t *y_factor;
char szFilename[32];
// Open file
sprintf(szFilename, "%d.pgm", iFrame);
fp = fopen(szFilename,"wb");
if(fp) {
// Write header
fprintf(fp, "P5\n%d %d\n255\n", width, height);
y_factor = pFrame->data[0];
for(j = 0; j < height; j++) {
fwrite(y_factor, width, 1, fp);
y_factor += pFrame->linesize[0];
}
fclose(fp);
}
}
void ffmpeg_dump_yuv(char *filename, AVPicture *pic, int width, int height)
{
FILE *fp =0;
int i,j,shift;
uint8_t *yuv_factor;
fp = fopen(filename,"wb");
if(fp) {
for(i = 0; i < 3; i++) {
shift = (i == 0 ? 0:1);
yuv_factor = pic->data[i];
for(j = 0; j < (height>>shift); j++) {
fwrite(yuv_factor,(width>>shift),1,fp);
yuv_factor += pic->linesize[i];
}
}
fclose(fp);
}
}
/* Print motion vector for each macroblock in this frame. If there is
* no motion vector in some macroblock, it prints a magic number NO_MV. */
void printMVMatrix(int index, AVFrame *pict, AVCodecContext *ctx)
{
const int mb_width = (ctx->width + 15) / 16;
const int mb_height = (ctx->height + 15) / 16;
const int mb_stride = mb_width + 1;
const int mv_sample_log2 = 4 - pict->motion_subsample_log2;
const int mv_stride = (mb_width << mv_sample_log2) + (ctx->codec_id == CODEC_ID_H264 ? 0 : 1);
const int quarter_sample = (ctx->flags & CODEC_FLAG_QPEL) != 0;
const int shift = 1 + quarter_sample;
FILE * fpMVFile;
char csMVFileName[100];
sprintf(csMVFileName, ".\\%d.txt", index);
fpMVFile = fopen(csMVFileName, "w");
int mb_y, mb_x, type, i;
for (mb_y = 0; mb_y < mb_height; mb_y++) {
for (mb_x = 0; mb_x < mb_width; mb_x++) {
const int mb_index = mb_x + mb_y * mb_stride;
if (pict->motion_val) {
for (type = 0; type < 3; type++) {
int direction = 0;
switch (type) {
case 0:
if (pict->pict_type != AV_PICTURE_TYPE_P)
continue;
direction = 0;
break;
case 1:
if (pict->pict_type != AV_PICTURE_TYPE_B)
continue;
direction = 0;
break;
case 2:
if (pict->pict_type != AV_PICTURE_TYPE_B)
continue;
direction = 1;
break;
}
if (!USES_LIST(pict->mb_type[mb_index], direction)) {
#define NO_MV 10000
if (IS_8X8(pict->mb_type[mb_index])) {
fprintf(fpMVFile, "%d\t%d\n", NO_MV, NO_MV);
fprintf(fpMVFile, "%d\t%d\n", NO_MV, NO_MV);
fprintf(fpMVFile, "%d\t%d\n", NO_MV, NO_MV);
fprintf(fpMVFile, "%d\t%d\n", NO_MV, NO_MV);
}
else if (IS_16X8(pict->mb_type[mb_index])) {
fprintf(fpMVFile, "%d\t%d\n", NO_MV, NO_MV);
fprintf(fpMVFile, "%d\t%d\n", NO_MV, NO_MV);
}
else if (IS_8X16(pict->mb_type[mb_index])) {
fprintf(fpMVFile, "%d\t%d\n", NO_MV, NO_MV);
fprintf(fpMVFile, "%d\t%d\n", NO_MV, NO_MV);
}
else {
fprintf(fpMVFile, "%d\t%d\n", NO_MV, NO_MV);
}
#undef NO_MV
continue;
}
if (IS_8X8(pict->mb_type[mb_index])) {
for (i = 0; i < 4; i++) {
int xy = (mb_x*2 + (i&1) + (mb_y*2 + (i>>1))*mv_stride) << (mv_sample_log2-1);
int dx = (pict->motion_val[direction][xy][0]>>shift);
int dy = (pict->motion_val[direction][xy][1]>>shift);
fprintf(fpMVFile, "%d\t%d\n", dx, dy);
}
}
else if (IS_16X8(pict->mb_type[mb_index])) {
for (i = 0; i < 2; i++) {
int xy = (mb_x*2 + (mb_y*2 + i)*mv_stride) << (mv_sample_log2-1);
int dx = (pict->motion_val[direction][xy][0]>>shift);
int dy = (pict->motion_val[direction][xy][1]>>shift);
if (IS_INTERLACED(pict->mb_type[mb_index]))
dy *= 2;
fprintf(fpMVFile, "%d\t%d\n", dx, dy);
}
}
else if (IS_8X16(pict->mb_type[mb_index])) {
for (i = 0; i < 2; i++) {
int xy = (mb_x*2 + i + mb_y*2*mv_stride) << (mv_sample_log2-1);
int dx = (pict->motion_val[direction][xy][0]>>shift);
int dy = (pict->motion_val[direction][xy][1]>>shift);
if (IS_INTERLACED(pict->mb_type[mb_index]))
dy *= 2;
fprintf(fpMVFile, "%d\t%d\n", dx, dy);
}
}
else {
int xy = (mb_x + mb_y*mv_stride) << mv_sample_log2;
int dx = (pict->motion_val[direction][xy][0]>>shift);
int dy = (pict->motion_val[direction][xy][1]>>shift);
fprintf(fpMVFile, "%d\t%d\n", dx, dy);
}
}
}
}
}
fclose(fpMVFile);
}
int main (int argc, const char * argv[])
{
AVFormatContext *pFormatCtx = NULL;
int i, videoStream;
AVCodecContext *pCodecCtx;
AVCodec *pCodec;
AVFrame *pFrame;
AVFrame *pFrameRGB;
AVPacket packet;
int frameFinished;
int numBytes;
uint8_t *buffer;
// Register all formats and codecs
av_register_all();
avformat_network_init();
// Open video file
if(avformat_open_input(&pFormatCtx, argv[1], NULL, NULL)!=0)
{
printf("Couldn't open file\n");
return -1; // Couldn't open file
}
// Retrieve stream information
if(av_find_stream_info(pFormatCtx)<0)
{
printf("Couldn't find stream information\n");
return -1; // Couldn't find stream information
}
// Dump information about file onto standard error
av_dump_format(pFormatCtx, 0, argv[1], false);
// Find the first video stream
videoStream=-1;
for(i=0; i<pFormatCtx->nb_streams; i++) {
if(pFormatCtx->streams[i]->codec->codec_type==AVMEDIA_TYPE_VIDEO)
{
videoStream=i;
break;
}
}
if(videoStream==-1)
{
printf("Didn't find a video stream\n");
return -1; // Didn't find a video stream
}
// Get a pointer to the codec context for the video stream
pCodecCtx=pFormatCtx->streams[videoStream]->codec;
// Find the decoder for the video stream
pCodec=avcodec_find_decoder(pCodecCtx->codec_id);
if(pCodec==NULL)
{
printf("Codec not found\n");
return -1; // Codec not found
}
// Open codec
if(avcodec_open(pCodecCtx, pCodec)<0)
{
printf("Could not open codec\n");
return -1; // Could not open codec
}
// Hack to correct wrong frame rates that seem to be generated by some codecs
if(pCodecCtx->time_base.num>1000 && pCodecCtx->time_base.den==1)
pCodecCtx->time_base.den=1000;
// Allocate video frame
pFrame=avcodec_alloc_frame();
// Allocate an AVFrame structure
//pFrameRGB=avcodec_alloc_frame();
//if(pFrameRGB==NULL)
// return -1;
// Determine required buffer size and allocate buffer
//numBytes=avpicture_get_size(PIX_FMT_RGB24, pCodecCtx->width,
// pCodecCtx->height);
//buffer=malloc(numBytes);
// Assign appropriate parts of buffer to image planes in pFrameRGB
//avpicture_fill((AVPicture *)pFrameRGB, buffer, PIX_FMT_RGB24,
// pCodecCtx->width, pCodecCtx->height);
// Read frames and save first five frames to disk
i=0;
printf("Extract MVs from video (mb_width=%d, mb_hight=%d):\n", (pCodecCtx->width + 15)/16, (pCodecCtx->height + 15)/16);
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);
// Did we get a video frame?
if(frameFinished)
{
if(i%50==0){
printf(" ", i);
}
printMVMatrix(i++, pFrame, pCodecCtx);
if (pFrame->pict_type == AV_PICTURE_TYPE_I){
printf("I");
}
else if(pFrame->pict_type == AV_PICTURE_TYPE_P){
printf("P");
printMVMatrix(i, pFrame, pCodecCtx);
}
else if(pFrame->pict_type == AV_PICTURE_TYPE_B){
printf("B");
}
else {
printf(".");
}
i++;
if(i%10==0) {
printf(" ");
if(i%50==0){
printf("[ %d ]\n", i);
}
}
/*
static struct SwsContext *img_convert_ctx;
// Convert the image into YUV format that SDL uses
if(img_convert_ctx == NULL) {
int w = pCodecCtx->width;
int h = pCodecCtx->height;
img_convert_ctx = sws_getContext(w, h,
pCodecCtx->pix_fmt,
w, h, PIX_FMT_RGB24, SWS_BICUBIC,
NULL, NULL, NULL);
if(img_convert_ctx == NULL) {
fprintf(stderr, "Cannot initialize the conversion context!\n");
exit(1);
}
}
int ret = sws_scale(img_convert_ctx, pFrame->data, pFrame->linesize, 0,
pCodecCtx->height, pFrameRGB->data, pFrameRGB->linesize);
// Save the frame to disk
SaveFrame(pFrameRGB, pCodecCtx->width, pCodecCtx->height, i++);
*/
}
}
// Free the packet that was allocated by av_read_frame
av_free_packet(&packet);
}
// Free the RGB image
//free(buffer);
//av_free(pFrameRGB);
// Free the YUV frame
av_free(pFrame);
// Close the codec
avcodec_close(pCodecCtx);
// Close the video file
av_close_input_file(pFormatCtx);
return 0;
}
]]>
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