FFmpeg H264解析 [英] FFmpeg H264 parsing
本文介绍了FFmpeg H264解析的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我使用FFmpeg解码H.264视频，用于以下程序：
#include< stdlib.h> ;
#include< stdio.h>
#include< string.h>
#include< signal.h>
#include< sys / time.h>
#include< time.h>
#include< libavcodec / avcodec.h>
#include< libavutil / mathematics.h>
#include< SDL / SDL.h>
void sigint_handler（int signal）{
printf（\\\
）;
exit（0）;
}
const char * window_title;
SDL_Surface * screen;
SDL_Overlay * yuv_overlay;
#define INBUF_SIZE 80000
/ *
*视频解码示例
* /
static long get_time_diff time_now）{
struct timeval time_now2;
gettimeofday（& time_now2,0）;
return time_now2.tv_sec * 1.e6 - time_now.tv_sec * 1.e6 + time_now2.tv_usec - time_now.tv_usec;
}
int video_open（AVCodecContext * avctx，const char * filename）{
int flags = SDL_HWSURFACE | SDL_ASYNCBLIT | SDL_HWACCEL;
int w，h;
flags | = SDL_RESIZABLE;
if（avctx-> width）{
w = avctx-> width;
h = avctx-> height;
} else {
w = 640;
h = 480;
}
if（SDL_Init（SDL_INIT_VIDEO）< 0）{
fprintf（stderr，SDL_INIT_VIDEO failed！\\\
）;
exit（1）;
}
screen = SDL_SetVideoMode（w，h，0，flags）;
if（！screen）{
fprintf（stderr，SDL：could not set video mode - exiting\\\
）;
return -1;
}
if（！window_title）
window_title = filename;
SDL_WM_SetCaption（window_title，window_title）;
yuv_overlay = SDL_CreateYUVOverlay（w，h，SDL_YV12_OVERLAY，screen）;
if（yuv_overlay-> hw_overlay）{
fprintf（stderr，Using hardware overlay！\\\
）;
}
return 0;
}
int main（int argc，char ** argv）{
AVCodec * codec;
AVCodecContext * c = NULL;
AVCodecParserContext * parser = NULL;
int frame，got_picture，len2，len;
const char * filename;
FILE * f;
AVFrame * picture;
char * arghwtf = malloc（INBUF_SIZE）;
char * luma = NULL;
char * chroma = NULL;
int i = 0;
uint64_t in_len;
int pts，dts;
struct timeval t;
float inv_fps = 1e6 / 23.98;
AVPacket avpkt;
SDL_Rect rect;
/ *注册所有编解码器* /
avcodec_register_all（）;
filename = argv [1];
av_init_packet（& avpkt）;
printf（解码文件％s ... \\\
，filename）;
/ *查找H.264视频解码器* /
codec = avcodec_find_decoder（CODEC_ID_H264）;
if（！codec）{
fprintf（stderr，codec not found\\\
）;
exit（1）;
}
c = avcodec_alloc_context3（codec）;
picture = avcodec_alloc_frame（）;
c-> skip_loop_filter = 48; // skiploopfilter = all
if（avcodec_open（c，codec）< 0）{
fprintf（stderr，could not open codec\）;
exit（1）;
}
/ *编解码器给出了帧大小，以样本为单位* /
parser = av_parser_init（c-> codec_id）;
parser-> flags | = PARSER_FLAG_ONCE;
f = fopen（filename，rb）;
if（！f）{
fprintf（stderr，can not open％s\\\
，filename）;
exit（1）;
}
frame = 0;
gettimeofday（& t，0）;
if（fread（arghwtf，1，INBUF_SIZE，f）== 0）{
exit（1）;
}
in_len = 80000;
while（in_len> 0&&！feof（f））{
len = av_parser_parse2（parser，c，& avpkt.data，& avpkt.size，arghwtf，in_len，
pts，dts，AV_NOPTS_VALUE）;
len2 = avcodec_decode_video2（c，picture，& got_picture，& avpkt）;
if（len2< 0）{
fprintf（stderr，Error during decode frame％d \\\
，frame）;
exit（1）;
}
if（got_picture）{
if（！screen）{
video_open（c，filename）;
rect.x = 0;
rect.y = 0;
rect.w = c-> width;
rect.h = c-> height;
inv_fps = av_q2d（c-> time_base）;
fprintf（stderr，w：％i h：％i \\\
，rect.w，rect.h）;
luma = malloc（c-> width * c-> height）;
chroma = malloc（c-> width * c-> height / 4）;
SDL_DisplayYUVOverlay（yuv_overlay，& rect）;
signal（SIGINT，sigint_handler）;
}
fprintf（stderr，\rDisplaying％c：frame％3d（％02d：％02d）...，av_get_pict_type_char（picture-> pict_type），frame / 1440， （帧/ 24）％60）;
fflush（stderr）; $ b¥b
SDL_LockYUVOverlay（yuv_overlay）;
for（i = 0; i c- height; i ++）{
memcpy（luma + i * c-> width，picture-> data [0] i * picture-> linesize [0]，c-> width）;
}
memcpy（yuv_overlay-> pixels [0]，luma，c-> width * c-> height）
for（i = 0; i c- height / 2; i ++）{
memcpy（chroma + i * c-> width / 2，picture-> data [2] i * picture-> linesize [2]，c-> width / 2）;
}
memcpy（yuv_overlay-> pixels [1]，chroma，c-> width * c-> height / 4）;
for（i = 0; i c- height / 2; i ++）{
memcpy（chroma + i * c-> width / 2，picture-> data [1] i * picture-> linesize [1]，c-> width / 2）;
}
memcpy（yuv_overlay-> pixels [2]，chroma，c-> width * c-> height / 4）;
SDL_UnlockYUVOverlay（yuv_overlay）;
SDL_DisplayYUVOverlay（yuv_overlay，& rect）;
while（get_time_diff（t）< inv_fps）{
sleep（1000）;
}
frame ++;
gettimeofday（& t，0）;
}
memcpy（arghwtf，arghwtf + len，80000-len）;
fread（arghwtf + 80000 - len，1，len，f）;
}
/ *一些编解码器，例如MPEG，以一帧的
延迟传输I和P帧。您必须执行以下操作才能获得
机会获取视频的最后一帧* /
avpkt.data = NULL;
avpkt.size = 0;
len = avcodec_decode_video2（c，picture，& got_picture，& avpkt）;
if（got_picture）{
printf（saving last frame％3d \\\
，frame）;
fflush（stdout）;
/ *在这里显示最后一帧，与上面的解码循环相同的代码。 * /
frame ++;
}
fclose（f）;
avcodec_close（c）;
av_free（c）;
av_free（picture）;
printf（\\\
）;
}
这会产生错误：
|| === H264_decoding，Debug === |
/ home / yoohoo / codeblocks /实时视频流/ H264_decoding / main.cpp ||在函数'int main（int，char **）'：
/ home / yoohoo / codeblocks /实时视频流/ H264_decoding / main.cpp | 107 |错误：从'void *'到'char *'的无效转换[-fpermissive]
/ home / yoohoo / codeblocks /实时视频流/ H264_decoding / main.cpp | 136 |警告：'AVFrame * avcodec_alloc_frame（）'已弃用（在/ home / yoohoo / ffmpeg_build / include / libavcodec / avcodec.h：3629）[-Wdeprecated-declarations] |
/ home / yoohoo / codeblocks /实时视频流/ H264_decoding / main.cpp | 136 |警告：'AVFrame * avcodec_alloc_frame（）'已弃用（在/ home / yoohoo / ffmpeg_build / include / libavcodec / avcodec.h：3629）[-Wdeprecated-declarations] |
/ home / yoohoo / codeblocks /实时视频流/ H264_decoding / main.cpp | 138 |错误：从'int'到'AVDiscard'的无效转换[-fpermissive] |
/ home / yoohoo / codeblocks /实时视频流/ H264_decoding / main.cpp | 140 |错误：'avcodec_open'没有在此范围内声明|
/ home / yoohoo / codeblocks /实时视频流/ H264_decoding / main.cpp | 163 |错误：无效从'char *'转换为'const uint8_t * {aka const unsigned char *}' ] |
/home/yoohoo/ffmpeg_build/include/libavcodec/avcodec.h|4465|error：初始化'int av_parser_parse2（AVCodecParserContext *，AVCodecContext *，uint8_t **，int *，const uint8_t *，int， int64_t，int64_t，int64_t）'[-fpermissive] |
/ home / yoohoo / codeblocks /实时视频流/ H264_decoding / main.cpp | 181 |错误：从'void *'到'char *'的无效转换[-fpermissive]
/ home / yoohoo / codeblocks /实时视频流/ H264_decoding / main.cpp | 182 |错误：从'void *'到'char *'的无效转换[-fpermissive]
/ home / yoohoo / codeblocks /实时视频流/ H264_decoding / main.cpp | 188 |错误：'av_get_pict_type_char'没有在此范围内声明|
/ home / yoohoo / codeblocks /实时视频流/ H264_decoding / main.cpp | 210 |错误：'sleep'未在此范围内声明|
|| ===构建完成：9错误，2警告=== |
我想知道这是一个不兼容的问题，因为我把这个C程序移动到C + +，需要在C ++中使用它。如何解决这些无效的转换问题？提前感谢！
解决方案
在您的代码的main（）函数中
char * arghwtf = malloc（INBUF_SIZE）;
您已通过使用返回void *的malloc函数分配内存，并且将此void * char *这就是为什么你会得到错误。
<$ c $ c> char * arghwtf =（char *）malloc（INBUF_SIZE）;
I am using FFmpeg to decoding H.264 video, for the following program:
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <signal.h>
#include <sys/time.h>
#include <time.h>
#include <libavcodec/avcodec.h>
#include <libavutil/mathematics.h>
#include <SDL/SDL.h>
void sigint_handler(int signal) {
printf("\n");
exit(0);
}
const char *window_title;
SDL_Surface *screen;
SDL_Overlay *yuv_overlay;
#define INBUF_SIZE 80000
/*
* Video decoding example
*/
static long get_time_diff(struct timeval time_now) {
struct timeval time_now2;
gettimeofday(&time_now2,0);
return time_now2.tv_sec*1.e6 - time_now.tv_sec*1.e6 + time_now2.tv_usec - time_now.tv_usec;
}
int video_open(AVCodecContext *avctx, const char *filename){
int flags = SDL_HWSURFACE|SDL_ASYNCBLIT|SDL_HWACCEL;
int w,h;
flags |= SDL_RESIZABLE;
if (avctx->width){
w = avctx->width;
h = avctx->height;
} else {
w = 640;
h = 480;
}
if(SDL_Init(SDL_INIT_VIDEO) < 0) {
fprintf(stderr, "SDL_INIT_VIDEO failed!\n");
exit(1);
}
screen = SDL_SetVideoMode(w, h, 0, flags);
if (!screen) {
fprintf(stderr, "SDL: could not set video mode - exiting\n");
return -1;
}
if (!window_title)
window_title = filename;
SDL_WM_SetCaption(window_title, window_title);
yuv_overlay = SDL_CreateYUVOverlay(w, h, SDL_YV12_OVERLAY, screen);
if (yuv_overlay->hw_overlay) {
fprintf(stderr, "Using hardware overlay!\n");
}
return 0;
}
int main(int argc, char **argv) {
AVCodec *codec;
AVCodecContext *c= NULL;
AVCodecParserContext *parser = NULL;
int frame, got_picture, len2, len;
const char *filename;
FILE *f;
AVFrame *picture;
char *arghwtf = malloc(INBUF_SIZE);
char *luma = NULL;
char *chroma = NULL;
int i=0;
uint64_t in_len;
int pts, dts;
struct timeval t;
float inv_fps = 1e6/23.98;
AVPacket avpkt;
SDL_Rect rect;
/* register all the codecs */
avcodec_register_all();
filename = argv[1];
av_init_packet(&avpkt);
printf("Decoding file %s...\n", filename);
/* find the H.264 video decoder */
codec = avcodec_find_decoder(CODEC_ID_H264);
if (!codec) {
fprintf(stderr, "codec not found\n");
exit(1);
}
c = avcodec_alloc_context3(codec);
picture = avcodec_alloc_frame();
c->skip_loop_filter = 48; // skiploopfilter=all
if (avcodec_open(c, codec) < 0) {
fprintf(stderr, "could not open codec\n");
exit(1);
}
/* the codec gives us the frame size, in samples */
parser = av_parser_init(c->codec_id);
parser->flags |= PARSER_FLAG_ONCE;
f = fopen(filename, "rb");
if (!f) {
fprintf(stderr, "could not open %s\n", filename);
exit(1);
}
frame = 0;
gettimeofday(&t, 0);
if(fread(arghwtf, 1, INBUF_SIZE, f) == 0) {
exit(1);
}
in_len = 80000;
while (in_len > 0 && !feof(f)) {
len = av_parser_parse2(parser, c, &avpkt.data, &avpkt.size, arghwtf, in_len,
pts, dts, AV_NOPTS_VALUE);
len2 = avcodec_decode_video2(c, picture, &got_picture, &avpkt);
if (len2 < 0) {
fprintf(stderr, "Error while decoding frame %d\n", frame);
exit(1);
}
if (got_picture) {
if(!screen) {
video_open(c, filename);
rect.x = 0;
rect.y = 0;
rect.w = c->width;
rect.h = c->height;
inv_fps = av_q2d(c->time_base);
fprintf(stderr, "w:%i h:%i\n", rect.w, rect.h);
luma = malloc(c->width*c->height);
chroma = malloc(c->width*c->height/4);
SDL_DisplayYUVOverlay(yuv_overlay, &rect);
signal(SIGINT, sigint_handler);
}
fprintf(stderr, "\rDisplaying %c:frame %3d (%02d:%02d)...", av_get_pict_type_char(picture->pict_type), frame, frame/1440, (frame/24)%60);
fflush(stderr);
SDL_LockYUVOverlay(yuv_overlay);
for(i=0;i<c->height;i++) {
memcpy(luma + i * c->width, picture->data[0] + i * picture->linesize[0], c->width);
}
memcpy(yuv_overlay->pixels[0], luma, c->width * c->height);
for(i=0;i<c->height/2;i++) {
memcpy(chroma + i * c->width/2, picture->data[2] + i * picture->linesize[2], c->width/2);
}
memcpy(yuv_overlay->pixels[1], chroma, c->width * c->height / 4);
for(i=0;i<c->height/2;i++) {
memcpy(chroma + i * c->width/2, picture->data[1] + i * picture->linesize[1], c->width/2);
}
memcpy(yuv_overlay->pixels[2], chroma, c->width * c->height / 4);
SDL_UnlockYUVOverlay(yuv_overlay);
SDL_DisplayYUVOverlay(yuv_overlay, &rect);
while(get_time_diff(t) < inv_fps) {
sleep(1000);
}
frame++;
gettimeofday(&t, 0);
}
memcpy(arghwtf, arghwtf + len, 80000-len);
fread(arghwtf + 80000 - len, 1, len, f);
}
/* some codecs, such as MPEG, transmit the I and P frame with a
latency of one frame. You must do the following to have a
chance to get the last frame of the video */
avpkt.data = NULL;
avpkt.size = 0;
len = avcodec_decode_video2(c, picture, &got_picture, &avpkt);
if (got_picture) {
printf("saving last frame %3d\n", frame);
fflush(stdout);
/* Display last frame here, same code as in the decoding loop above. */
frame++;
}
fclose(f);
avcodec_close(c);
av_free(c);
av_free(picture);
printf("\n");
}
It gives error:
||=== H264_decoding, Debug ===|
/home/yoohoo/codeblocks/Real-time video streaming/H264_decoding/main.cpp||In function ‘int main(int, char**)’:|
/home/yoohoo/codeblocks/Real-time video streaming/H264_decoding/main.cpp|107|error: invalid conversion from ‘void*’ to ‘char*’ [-fpermissive]|
/home/yoohoo/codeblocks/Real-time video streaming/H264_decoding/main.cpp|136|warning: ‘AVFrame* avcodec_alloc_frame()’ is deprecated (declared at /home/yoohoo/ffmpeg_build/include/libavcodec/avcodec.h:3629) [-Wdeprecated-declarations]|
/home/yoohoo/codeblocks/Real-time video streaming/H264_decoding/main.cpp|136|warning: ‘AVFrame* avcodec_alloc_frame()’ is deprecated (declared at /home/yoohoo/ffmpeg_build/include/libavcodec/avcodec.h:3629) [-Wdeprecated-declarations]|
/home/yoohoo/codeblocks/Real-time video streaming/H264_decoding/main.cpp|138|error: invalid conversion from ‘int’ to ‘AVDiscard’ [-fpermissive]|
/home/yoohoo/codeblocks/Real-time video streaming/H264_decoding/main.cpp|140|error: ‘avcodec_open’ was not declared in this scope|
/home/yoohoo/codeblocks/Real-time video streaming/H264_decoding/main.cpp|163|error: invalid conversion from ‘char*’ to ‘const uint8_t* {aka const unsigned char*}’ [-fpermissive]|
/home/yoohoo/ffmpeg_build/include/libavcodec/avcodec.h|4465|error: initializing argument 5 of ‘int av_parser_parse2(AVCodecParserContext*, AVCodecContext*, uint8_t**, int*, const uint8_t*, int, int64_t, int64_t, int64_t)’ [-fpermissive]|
/home/yoohoo/codeblocks/Real-time video streaming/H264_decoding/main.cpp|181|error: invalid conversion from ‘void*’ to ‘char*’ [-fpermissive]|
/home/yoohoo/codeblocks/Real-time video streaming/H264_decoding/main.cpp|182|error: invalid conversion from ‘void*’ to ‘char*’ [-fpermissive]|
/home/yoohoo/codeblocks/Real-time video streaming/H264_decoding/main.cpp|188|error: ‘av_get_pict_type_char’ was not declared in this scope|
/home/yoohoo/codeblocks/Real-time video streaming/H264_decoding/main.cpp|210|error: ‘sleep’ was not declared in this scope|
||=== Build finished: 9 errors, 2 warnings ===|
I am wondering it is an incompatible problem due to I move this C program to C++, but I finally need to use it in C++. How to solve these invalid conversion problem? Thanks in advance!
解决方案
In main() function of your code
char *arghwtf = malloc(INBUF_SIZE);
You have allocated memory by using malloc function which returns void * , and you are assigning this void * to char * that's why you are getting errors. You have to typecast it into char *.
Instead try this.
char *arghwtf =(char *) malloc(INBUF_SIZE);
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