我试图使用ffmpeg库将视频流从我的应用程序发送到媒体服务器（在本例中为wowza）。我已经能够反过来使用RTSP流，但我在编写RTSP流时遇到了一些问题。
我找到了一些例子并试图利用相关的比特。代码如下。我尽可能地简化了它。我只想将一个H264比特流发送到wowza服务器并且它可以处理它。
我得到一个＆＃34;整数除以零＆＃34;当我尝试发送数据包时，无论何时在 av_interleaved_write_frame 函数中。该异常看起来与数据包时间戳未正确设置有关。我尝试了不同的值，可以通过设置一些人为的值来超越异常，但写入调用失败。
#include <iostream>
#include <fstream>
#include <sstream>
#include <cstring>
#include "stdafx.h"
#include "windows.h"
extern "C"
{
#include <libavcodec\avcodec.h>
#include <libavformat\avformat.h>
#include <libavformat\avio.h>
#include <libswscale\swscale.h>
}
using namespace std;
static int video_is_eof;
#define STREAM_DURATION 50.0
#define STREAM_FRAME_RATE 25 /* 25 images/s */
#define STREAM_PIX_FMT AV_PIX_FMT_YUV420P /* default pix_fmt */
#define VIDEO_CODEC_ID CODEC_ID_H264
static int sws_flags = SWS_BICUBIC;
/* video output */
static AVFrame *frame;
static AVPicture src_picture, dst_picture;
static int frame_count;
static int write_frame(AVFormatContext *fmt_ctx, const AVRational *time_base, AVStream *st, AVPacket *pkt)
{
/* rescale output packet timestamp values from codec to stream timebase */
pkt->pts = av_rescale_q_rnd(pkt->pts, *time_base, st->time_base, AVRounding(AV_ROUND_NEAR_INF | AV_ROUND_PASS_MINMAX));
pkt->dts = av_rescale_q_rnd(pkt->dts, *time_base, st->time_base, AVRounding(AV_ROUND_NEAR_INF | AV_ROUND_PASS_MINMAX));
pkt->duration = av_rescale_q(pkt->duration, *time_base, st->time_base);
pkt->stream_index = st->index;
// Exception occurs here.
return av_interleaved_write_frame(fmt_ctx, pkt);
}
/* Add an output stream. */
static AVStream *add_stream(AVFormatContext *oc, AVCodec **codec, enum AVCodecID codec_id)
{
AVCodecContext *c;
AVStream *st;
/* find the encoder */
*codec = avcodec_find_encoder(codec_id);
if (!(*codec)) {
fprintf(stderr, "Could not find encoder for '%s'\n", avcodec_get_name(codec_id));
exit(1);
}
st = avformat_new_stream(oc, *codec);
if (!st) {
fprintf(stderr, "Could not allocate stream\n");
exit(1);
}
st->id = oc->nb_streams - 1;
c = st->codec;
c->codec_id = codec_id;
c->bit_rate = 400000;
c->width = 352;
c->height = 288;
c->time_base.den = STREAM_FRAME_RATE;
c->time_base.num = 1;
c->gop_size = 12; /* emit one intra frame every twelve frames at most */
c->pix_fmt = STREAM_PIX_FMT;
return st;
}
static void open_video(AVFormatContext *oc, AVCodec *codec, AVStream *st)
{
int ret;
AVCodecContext *c = st->codec;
/* open the codec */
ret = avcodec_open2(c, codec, NULL);
if (ret < 0) {
fprintf(stderr, "Could not open video codec: ");
exit(1);
}
/* allocate and init a re-usable frame */
frame = av_frame_alloc();
if (!frame) {
fprintf(stderr, "Could not allocate video frame\n");
exit(1);
}
frame->format = c->pix_fmt;
frame->width = c->width;
frame->height = c->height;
/* Allocate the encoded raw picture. */
ret = avpicture_alloc(&dst_picture, c->pix_fmt, c->width, c->height);
if (ret < 0) {
fprintf(stderr, "Could not allocate picture: ");
exit(1);
}
/* copy data and linesize picture pointers to frame */
*((AVPicture *)frame) = dst_picture;
}
/* Prepare a dummy image. */
static void fill_yuv_image(AVPicture *pict, int frame_index, int width, int height)
{
int x, y, i;
i = frame_index;
/* Y */
for (y = 0; y < height; y++)
for (x = 0; x < width; x++)
pict->data[0][y * pict->linesize[0] + x] = x + y + i * 3;
/* Cb and Cr */
for (y = 0; y < height / 2; y++) {
for (x = 0; x < width / 2; x++) {
pict->data[1][y * pict->linesize[1] + x] = 128 + y + i * 2;
pict->data[2][y * pict->linesize[2] + x] = 64 + x + i * 5;
}
}
}
static void write_video_frame(AVFormatContext *oc, AVStream *st, int flush)
{
int ret;
AVCodecContext *c = st->codec;
if (!flush) {
fill_yuv_image(&dst_picture, frame_count, c->width, c->height);
}
AVPacket pkt = { 0 };
int got_packet;
av_init_packet(&pkt);
/* encode the image */
frame->pts = frame_count;
ret = avcodec_encode_video2(c, &pkt, flush ? NULL : frame, &got_packet);
if (ret < 0) {
fprintf(stderr, "Error encoding video frame:");
exit(1);
}
/* If size is zero, it means the image was buffered. */
if (got_packet) {
ret = write_frame(oc, &c->time_base, st, &pkt);
}
else {
if (flush) {
video_is_eof = 1;
}
ret = 0;
}
if (ret < 0) {
fprintf(stderr, "Error while writing video frame: ");
exit(1);
}
frame_count++;
}
static void close_video(AVFormatContext *oc, AVStream *st)
{
avcodec_close(st->codec);
av_free(src_picture.data[0]);
av_free(dst_picture.data[0]);
av_frame_free(&frame);
}
int _tmain(int argc, _TCHAR* argv[])
{
printf("starting...\n");
const char *filename = "rtsp://test:password@192.168.33.19:1935/ffmpeg/0";
AVOutputFormat *fmt;
AVFormatContext *oc;
AVStream *video_st;
AVCodec *video_codec;
double video_time;
int flush, ret;
/* Initialize libavcodec, and register all codecs and formats. */
av_register_all();
avformat_network_init();
AVOutputFormat* oFmt = av_oformat_next(NULL);
while (oFmt) {
if (oFmt->video_codec == VIDEO_CODEC_ID) {
break;
}
oFmt = av_oformat_next(oFmt);
}
if (!oFmt) {
printf("Could not find the required output format.\n");
exit(1);
}
/* allocate the output media context */
avformat_alloc_output_context2(&oc, oFmt, "rtsp", filename);
if (!oc) {
printf("Could not set the output media context.\n");
exit(1);
}
fmt = oc->oformat;
if (!fmt) {
printf("Could not create the output format.\n");
exit(1);
}
video_st = NULL;
cout << "Codec = " << avcodec_get_name(fmt->video_codec) << endl;
if (fmt->video_codec != AV_CODEC_ID_NONE)
{
video_st = add_stream(oc, &video_codec, fmt->video_codec);
}
/* Now that all the parameters are set, we can open the video codec and allocate the necessary encode buffers. */
if (video_st) {
open_video(oc, video_codec, video_st);
}
av_dump_format(oc, 0, filename, 1);
char errorBuff[80];
if (!(fmt->flags & AVFMT_NOFILE)) {
ret = avio_open(&oc->pb, filename, AVIO_FLAG_WRITE);
if (ret < 0) {
fprintf(stderr, "Could not open outfile '%s': %s", filename, av_make_error_string(errorBuff, 80, ret));
return 1;
}
}
flush = 0;
while (video_st && !video_is_eof) {
/* Compute current video time. */
video_time = (video_st && !video_is_eof) ? video_st->pts.val * av_q2d(video_st->time_base) : INFINITY;
if (!flush && (!video_st || video_time >= STREAM_DURATION)) {
flush = 1;
}
if (video_st && !video_is_eof) {
write_video_frame(oc, video_st, flush);
}
}
if (video_st) {
close_video(oc, video_st);
}
if ((fmt->flags & AVFMT_NOFILE)) {
avio_close(oc->pb);
}
avformat_free_context(oc);
printf("finished.\n");
getchar();
return 0;
}
有没有人对如何成功设置数据包时间戳有任何见解？
答案 0 :(得分：7)
我通过在我的Windows实例上构建ffmpeg并调试av_interleaved_write_frame调用来解决整数除以零。事实证明，没有在视频流对象上设置导致异常的pts。
将以下行添加到main函数的while循环中解决了问题：
video_st->pts.val += av_rescale_q(1, video_st->codec->time_base, video_st->time_base);
这是一个样本，用于通过ffmpeg的RTSP管道将H264编码的虚拟流传送到Wowza服务器。
// Roughly based on: https://ffmpeg.org/doxygen/trunk/muxing_8c-source.html
#include <chrono>
#include <thread>
#include <tchar.h>
extern "C"
{
#include <libavcodec\avcodec.h>
#include <libavformat\avformat.h>
#include <libavformat\avio.h>
#include <libswscale\swscale.h>
#include <libavutil\time.h>
}
#pragma comment(lib,"libavformat/libavformat.a")
#pragma comment(lib,"libavcodec/libavcodec.a")
#pragma comment(lib,"libavutil/libavutil.a")
#pragma comment(lib,"libswscale/libswscale.a")
#pragma comment(lib,"x264.lib")
#pragma comment(lib,"libswresample/libswresample.a")
using namespace std;
static int video_is_eof;
#define STREAM_DURATION 20
#define STREAM_FRAME_RATE 25 /* 25 images/s */
#define STREAM_PIX_FMT AV_PIX_FMT_YUV420P /* default pix_fmt */ //AV_PIX_FMT_NV12;
#define VIDEO_CODEC_ID CODEC_ID_H264
/* video output */
static AVFrame *frame;
static AVPicture src_picture, dst_picture;
/* Add an output stream. */
static AVStream *add_stream(AVFormatContext *oc, AVCodec **codec, enum AVCodecID codec_id)
{
AVCodecContext *c;
AVStream *st;
/* find the encoder */
*codec = avcodec_find_encoder(codec_id);
if (!(*codec)) {
av_log(NULL, AV_LOG_ERROR, "Could not find encoder for '%s'.\n", avcodec_get_name(codec_id));
}
else {
st = avformat_new_stream(oc, *codec);
if (!st) {
av_log(NULL, AV_LOG_ERROR, "Could not allocate stream.\n");
}
else {
st->id = oc->nb_streams - 1;
st->time_base.den = st->pts.den = 90000;
st->time_base.num = st->pts.num = 1;
c = st->codec;
c->codec_id = codec_id;
c->bit_rate = 400000;
c->width = 352;
c->height = 288;
c->time_base.den = STREAM_FRAME_RATE;
c->time_base.num = 1;
c->gop_size = 12; /* emit one intra frame every twelve frames at most */
c->pix_fmt = STREAM_PIX_FMT;
}
}
return st;
}
static int open_video(AVFormatContext *oc, AVCodec *codec, AVStream *st)
{
int ret;
AVCodecContext *c = st->codec;
/* open the codec */
ret = avcodec_open2(c, codec, NULL);
if (ret < 0) {
av_log(NULL, AV_LOG_ERROR, "Could not open video codec.\n", avcodec_get_name(c->codec_id));
}
else {
/* allocate and init a re-usable frame */
frame = av_frame_alloc();
if (!frame) {
av_log(NULL, AV_LOG_ERROR, "Could not allocate video frame.\n");
ret = -1;
}
else {
frame->format = c->pix_fmt;
frame->width = c->width;
frame->height = c->height;
/* Allocate the encoded raw picture. */
ret = avpicture_alloc(&dst_picture, c->pix_fmt, c->width, c->height);
if (ret < 0) {
av_log(NULL, AV_LOG_ERROR, "Could not allocate picture.\n");
}
else {
/* copy data and linesize picture pointers to frame */
*((AVPicture *)frame) = dst_picture;
}
}
}
return ret;
}
/* Prepare a dummy image. */
static void fill_yuv_image(AVPicture *pict, int frame_index, int width, int height)
{
int x, y, i;
i = frame_index;
/* Y */
for (y = 0; y < height; y++)
for (x = 0; x < width; x++)
pict->data[0][y * pict->linesize[0] + x] = x + y + i * 3;
/* Cb and Cr */
for (y = 0; y < height / 2; y++) {
for (x = 0; x < width / 2; x++) {
pict->data[1][y * pict->linesize[1] + x] = 128 + y + i * 2;
pict->data[2][y * pict->linesize[2] + x] = 64 + x + i * 5;
}
}
}
static int write_video_frame(AVFormatContext *oc, AVStream *st, int frameCount)
{
int ret = 0;
AVCodecContext *c = st->codec;
fill_yuv_image(&dst_picture, frameCount, c->width, c->height);
AVPacket pkt = { 0 };
int got_packet;
av_init_packet(&pkt);
/* encode the image */
frame->pts = frameCount;
ret = avcodec_encode_video2(c, &pkt, frame, &got_packet);
if (ret < 0) {
av_log(NULL, AV_LOG_ERROR, "Error encoding video frame.\n");
}
else {
if (got_packet) {
pkt.stream_index = st->index;
pkt.pts = av_rescale_q_rnd(pkt.pts, c->time_base, st->time_base, AVRounding(AV_ROUND_NEAR_INF | AV_ROUND_PASS_MINMAX));
ret = av_write_frame(oc, &pkt);
if (ret < 0) {
av_log(NULL, AV_LOG_ERROR, "Error while writing video frame.\n");
}
}
}
return ret;
}
int _tmain(int argc, _TCHAR* argv[])
{
printf("starting...\n");
const char *url = "rtsp://test:password@192.168.33.19:1935/ffmpeg/0";
//const char *url = "rtsp://192.168.33.19:1935/ffmpeg/0";
AVFormatContext *outContext;
AVStream *video_st;
AVCodec *video_codec;
int ret = 0, frameCount = 0;
av_log_set_level(AV_LOG_DEBUG);
//av_log_set_level(AV_LOG_TRACE);
av_register_all();
avformat_network_init();
avformat_alloc_output_context2(&outContext, NULL, "rtsp", url);
if (!outContext) {
av_log(NULL, AV_LOG_FATAL, "Could not allocate an output context for '%s'.\n", url);
goto end;
}
if (!outContext->oformat) {
av_log(NULL, AV_LOG_FATAL, "Could not create the output format for '%s'.\n", url);
goto end;
}
video_st = add_stream(outContext, &video_codec, VIDEO_CODEC_ID);
/* Now that all the parameters are set, we can open the video codec and allocate the necessary encode buffers. */
if (video_st) {
av_log(NULL, AV_LOG_DEBUG, "Video stream codec %s.\n ", avcodec_get_name(video_st->codec->codec_id));
ret = open_video(outContext, video_codec, video_st);
if (ret < 0) {
av_log(NULL, AV_LOG_FATAL, "Open video stream failed.\n");
goto end;
}
}
else {
av_log(NULL, AV_LOG_FATAL, "Add video stream for the codec '%s' failed.\n", avcodec_get_name(VIDEO_CODEC_ID));
goto end;
}
av_dump_format(outContext, 0, url, 1);
ret = avformat_write_header(outContext, NULL);
if (ret != 0) {
av_log(NULL, AV_LOG_ERROR, "Failed to connect to RTSP server for '%s'.\n", url);
goto end;
}
printf("Press any key to start streaming...\n");
getchar();
auto startSend = std::chrono::system_clock::now();
while (video_st) {
frameCount++;
auto startFrame = std::chrono::system_clock::now();
ret = write_video_frame(outContext, video_st, frameCount);
if (ret < 0) {
av_log(NULL, AV_LOG_ERROR, "Write video frame failed.\n", url);
goto end;
}
auto streamDuration = std::chrono::duration_cast<chrono::milliseconds>(std::chrono::system_clock::now() - startSend).count();
printf("Elapsed time %ldms, video stream pts %ld.\n", streamDuration, video_st->pts.val);
if (streamDuration / 1000.0 > STREAM_DURATION) {
break;
}
else {
auto frameDuration = std::chrono::duration_cast<chrono::milliseconds>(std::chrono::system_clock::now() - startFrame).count();
std::this_thread::sleep_for(std::chrono::milliseconds((long)(1000.0 / STREAM_FRAME_RATE - frameDuration)));
}
}
if (video_st) {
avcodec_close(video_st->codec);
av_free(src_picture.data[0]);
av_free(dst_picture.data[0]);
av_frame_free(&frame);
}
avformat_free_context(outContext);
end:
printf("finished.\n");
getchar();
return 0;
}