k
/
ffmpeg_develop_doc
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Update (转)FFMpeg写MP4文件例子分析.c

Browse Source
pull/1/head
wenchao1024 3 years ago committed by GitHub
parent 3160e2bf99
commit dbe941c078
No known key found for this signature in database
GPG Key ID: 4AEE18F83AFDEB23
1 changed files with 514 additions and 119 deletions
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
Show Stats Download Patch File Download Diff File
  1. 617
      (转)FFMpeg写MP4文件例子分析.c

617
(转)FFMpeg写MP4文件例子分析.c
Unescape View File

@ -1,151 +1,546 @@
/**
使用FFMpeg可以很方便的对音视频进行编码，并且写文件。
这段时间看了FFMpeg提供的例子muxing.c，我略微修改了下源代码，使其生成一个MP4文件，音频使用AAC编码，视频使用H.264编码。代码很简单，我就不做说明了，代码如下。
下面的代码是将5幅1280*720大小的图片进行编码，并且写到文件中。
以后我们继续写如何将DirectShow中采集的音视频数据编码并生成MP4文件。
*/
/* 5 seconds stream duration */
#define STREAM_DURATION 5.0
#define STREAM_FRAME_RATE 25 /* 25 images/s */
#define STREAM_NB_FRAMES ((int)(STREAM_DURATION * STREAM_FRAME_RATE))
#define STREAM_PIX_FMT PIX_FMT_YUV420P /* default pix_fmt */
static int sws_flags = SWS_BICUBIC;
/**************************************************************/
/* audio output */
代码有些乱，但希望能抛砖引玉，对学习这方面的朋友有帮助。
static float t, tincr, tincr2;
static int16_t *samples;
static uint8_t *audio_outbuf;
static int audio_outbuf_size;
static int audio_input_frame_size;
/*
* add an audio output stream
*/
static AVStream *add_audio_stream(AVFormatContext *oc, enum CodecID codec_id)
{
AVCodecContext *c;
AVStream *st;
CFile file[5];
BYTE *szTxt[5];
st = avformat_new_stream(oc, NULL);
if (!st) {
fprintf(stderr, "Could not alloc stream\n");
exit(1);
}
st->id = 1;
int nWidth = 0;
int nHeight= 0;
c = st->codec;
c->codec_id = codec_id;
c->codec_type = AVMEDIA_TYPE_AUDIO;
int nDataLen=0;
/* put sample parameters */
c->sample_fmt = AV_SAMPLE_FMT_S16;
c->bit_rate = 64000;
c->sample_rate = 44100;
c->channels = 2;
int nLen;
// some formats want stream headers to be separate
if (oc->oformat->flags & AVFMT_GLOBALHEADER)
c->flags |= CODEC_FLAG_GLOBAL_HEADER;
CString csFileName;
for (int fileI = 1; fileI <= 5; fileI ++)
return st;
}
static void open_audio(AVFormatContext *oc, AVStream *st)
{
csFileName.Format("e:\\pics\\%d.bmp", fileI);
file[fileI - 1].Open(csFileName,CFile::modeRead | CFile::typeBinary);
nLen = file[fileI - 1].GetLength();
AVCodecContext *c;
AVCodec *codec;
szTxt[fileI -1] = new BYTE[nLen];
file[fileI - 1].Read(szTxt[fileI - 1], nLen);
file[fileI - 1].Close();
c = st->codec;
//BMP bmi;//BITMAPINFO bmi;
//int nHeadLen = sizeof(BMP);
BITMAPFILEHEADER bmpFHeader;
BITMAPINFOHEADER bmpIHeader;
memcpy(&bmpFHeader,szTxt[fileI -1],sizeof(BITMAPFILEHEADER));
/* find the audio encoder */
codec = avcodec_find_encoder(c->codec_id);
if (!codec) {
fprintf(stderr, "codec not found\n");
exit(1);
}
int nHeadLen = bmpFHeader.bfOffBits - sizeof(BITMAPFILEHEADER);
memcpy(&bmpIHeader,szTxt[fileI - 1]+sizeof(BITMAPFILEHEADER),nHeadLen);
/* open it */
if (avcodec_open(c, codec) < 0) {
fprintf(stderr, "could not open codec\n");
exit(1);
}
nWidth = bmpIHeader.biWidth;// 464;// bmi.bmpInfo.bmiHeader.biWidth;// ;
nHeight = bmpIHeader.biHeight;//362;// bmi.bmpInfo.bmiHeader.biHeight;// ;
/* init signal generator */
t = 0;
tincr = 2 * M_PI * 110.0 / c->sample_rate;
/* increment frequency by 110 Hz per second */
tincr2 = 2 * M_PI * 110.0 / c->sample_rate / c->sample_rate;
audio_outbuf_size = 10000;
audio_outbuf = (uint8_t *)av_malloc(audio_outbuf_size);
/* ugly hack for PCM codecs (will be removed ASAP with new PCM
support to compute the input frame size in samples */
if (c->frame_size <= 1) {
audio_input_frame_size = audio_outbuf_size / c->channels;
switch(st->codec->codec_id) {
case CODEC_ID_PCM_S16LE:
case CODEC_ID_PCM_S16BE:
case CODEC_ID_PCM_U16LE:
case CODEC_ID_PCM_U16BE:
audio_input_frame_size >>= 1;
break;
default:
break;
}
} else {
audio_input_frame_size = c->frame_size;
}
samples = (int16_t *)av_malloc(audio_input_frame_size * 2 * c->channels);
}
szTxt[fileI - 1] += bmpFHeader.bfOffBits;
nDataLen = nLen-bmpFHeader.bfOffBits;
/* prepare a 16 bit dummy audio frame of 'frame_size' samples and
'nb_channels' channels */
static void get_audio_frame(int16_t *samples, int frame_size, int nb_channels)
{
int j, i, v;
int16_t *q;
q = samples;
for (j = 0; j < frame_size; j++) {
v = (int)(sin(t) * 10000);
for(i = 0; i < nb_channels; i++)
*q++ = v;
t += tincr;
tincr += tincr2;
}
}
av_register_all();
avcodec_register_all();
AVFrame *m_pRGBFrame = new AVFrame[1]; //RGB帧数据
AVFrame *m_pYUVFrame = new AVFrame[1];; //YUV帧数据
AVCodecContext *c= NULL;
AVCodecContext *in_c= NULL;
AVCodec *pCodecH264; //编码器
uint8_t * yuv_buff;//
//查找h264编码器
pCodecH264 = avcodec_find_encoder(CODEC_ID_H264);
if(!pCodecH264)
static void write_audio_frame(AVFormatContext *oc, AVStream *st)
{
fprintf(stderr, "h264 codec not found\n");
AVCodecContext *c;
AVPacket pkt;
av_init_packet(&pkt);
c = st->codec;
get_audio_frame(samples, audio_input_frame_size, c->channels);
pkt.size = avcodec_encode_audio(c, audio_outbuf, audio_outbuf_size, samples);
if (c->coded_frame && c->coded_frame->pts != AV_NOPTS_VALUE)
pkt.pts= av_rescale_q(c->coded_frame->pts, c->time_base, st->time_base);
pkt.flags |= AV_PKT_FLAG_KEY;
pkt.stream_index = st->index;
pkt.data = audio_outbuf;
/* write the compressed frame in the media file */
if (av_interleaved_write_frame(oc, &pkt) != 0) {
fprintf(stderr, "Error while writing audio frame\n");
exit(1);
}
}
static void close_audio(AVFormatContext *oc, AVStream *st)
{
avcodec_close(st->codec);
av_free(samples);
av_free(audio_outbuf);
}
c= avcodec_alloc_context3(pCodecH264);
c->bit_rate = 3000000;// put sample parameters
c->width =nWidth;//
c->height = nHeight;//
// frames per second
AVRational rate;
rate.num = 1;
rate.den = 25;
c->time_base= rate;//(AVRational){1,25};
c->gop_size = 10; // emit one intra frame every ten frames
c->max_b_frames=1;
c->thread_count = 1;
c->pix_fmt = PIX_FMT_YUV420P;//PIX_FMT_RGB24;
//av_opt_set(c->priv_data, /*"preset"*/"libvpx-1080p.ffpreset", /*"slow"*/NULL, 0);
//打开编码器
if(avcodec_open2(c,pCodecH264,NULL)<0)
TRACE("不能打开编码库");
int size = c->width * c->height;
yuv_buff = (uint8_t *) malloc((size * 3) / 2); // size for YUV 420
//将rgb图像数据填充rgb帧
uint8_t * rgb_buff = new uint8_t[nDataLen];
//图象编码
int outbuf_size=100000;
uint8_t * outbuf= (uint8_t*)malloc(outbuf_size);
int u_size = 0;
FILE *f=NULL;
char * filename = "e:\\pics\\myData.h264";
f = fopen(filename, "wb");
if (!f)
/**************************************************************/
/* video output */
static AVFrame *picture, *tmp_picture;
static uint8_t *video_outbuf;
static int frame_count, video_outbuf_size;
/* add a video output stream */
static AVStream *add_video_stream(AVFormatContext *oc, enum CodecID codec_id)
{
TRACE( "could not open %s\n", filename);
AVCodecContext *c;
AVStream *st;
AVCodec *codec;
st = avformat_new_stream(oc, NULL);
if (!st) {
fprintf(stderr, "Could not alloc stream\n");
exit(1);
}
//初始化SwsContext
SwsContext * scxt = sws_getContext(c->width,c->height,PIX_FMT_BGR24,c->width,c->height,PIX_FMT_YUV420P,SWS_POINT,NULL,NULL,NULL);
c = st->codec;
/* find the video encoder */
codec = avcodec_find_encoder(codec_id);
if (!codec) {
fprintf(stderr, "codec not found\n");
exit(1);
}
avcodec_get_context_defaults3(c, codec);
c->codec_id = codec_id;
/* put sample parameters */
c->bit_rate = /*400000*/3000000;
/* resolution must be a multiple of two */
c->width = /*352*/640;
c->height = /*288*/480;
/* time base: this is the fundamental unit of time (in seconds) in terms
of which frame timestamps are represented. for fixed-fps content,
timebase should be 1/framerate and timestamp increments should be
identically 1. */
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;
if (c->codec_id == CODEC_ID_MPEG2VIDEO) {
/* just for testing, we also add B frames */
c->max_b_frames = 2;
}
if (c->codec_id == CODEC_ID_MPEG1VIDEO){
/* Needed to avoid using macroblocks in which some coeffs overflow.
This does not happen with normal video, it just happens here as
the motion of the chroma plane does not match the luma plane. */
c->mb_decision=2;
}
// some formats want stream headers to be separate
if (oc->oformat->flags & AVFMT_GLOBALHEADER)
c->flags |= CODEC_FLAG_GLOBAL_HEADER;
AVPacket avpkt;
//AVFrame *pTFrame=new AVFrame
for (int i=0;i<250;++i)
return st;
}
static AVFrame *alloc_picture(enum PixelFormat pix_fmt, int width, int height)
{
AVFrame *picture;
uint8_t *picture_buf;
int size;
picture = avcodec_alloc_frame();
if (!picture)
return NULL;
size = avpicture_get_size(pix_fmt, width, height);
picture_buf = (uint8_t *)av_malloc(size);
if (!picture_buf) {
av_free(picture);
return NULL;
}
avpicture_fill((AVPicture *)picture, picture_buf,
pix_fmt, width, height);
return picture;
}
//AVFrame *m_pYUVFrame = new AVFrame[1];
static void open_video(AVFormatContext *oc, AVStream *st)
{
AVCodec *codec;
AVCodecContext *c;
int index = (i / 25) % 5;
memcpy(rgb_buff,szTxt[index],nDataLen);
c = st->codec;
avpicture_fill((AVPicture*)m_pRGBFrame, (uint8_t*)rgb_buff, PIX_FMT_RGB24, nWidth, nHeight);
/* find the video encoder */
codec = avcodec_find_encoder(c->codec_id);
if (!codec) {
fprintf(stderr, "codec not found\n");
exit(1);
}
//将YUV buffer 填充YUV Frame
avpicture_fill((AVPicture*)m_pYUVFrame, (uint8_t*)yuv_buff, PIX_FMT_YUV420P, nWidth, nHeight);
/* open the codec */
if (avcodec_open(c, codec) < 0) {
fprintf(stderr, "could not open codec\n");
exit(1);
}
// 翻转RGB图像
m_pRGBFrame->data[0] += m_pRGBFrame->linesize[0] * (nHeight - 1);
m_pRGBFrame->linesize[0] *= -1;
m_pRGBFrame->data[1] += m_pRGBFrame->linesize[1] * (nHeight / 2 - 1);
m_pRGBFrame->linesize[1] *= -1;
m_pRGBFrame->data[2] += m_pRGBFrame->linesize[2] * (nHeight / 2 - 1);
m_pRGBFrame->linesize[2] *= -1;
video_outbuf = NULL;
if (!(oc->oformat->flags & AVFMT_RAWPICTURE)) {
/* allocate output buffer */
/* XXX: API change will be done */
/* buffers passed into lav* can be allocated any way you prefer,
as long as they're aligned enough for the architecture, and
they're freed appropriately (such as using av_free for buffers
allocated with av_malloc) */
video_outbuf_size = 200000;
video_outbuf = (uint8_t *)av_malloc(video_outbuf_size);
}
/* allocate the encoded raw picture */
picture = alloc_picture(c->pix_fmt, c->width, c->height);
if (!picture) {
fprintf(stderr, "Could not allocate picture\n");
exit(1);
}
//将RGB转化为YUV
sws_scale(scxt,m_pRGBFrame->data,m_pRGBFrame->linesize,0,c->height,m_pYUVFrame->data,m_pYUVFrame->linesize);
/* if the output format is not YUV420P, then a temporary YUV420P
picture is needed too. It is then converted to the required
output format */
tmp_picture = NULL;
if (c->pix_fmt != PIX_FMT_YUV420P) {
tmp_picture = alloc_picture(PIX_FMT_YUV420P, c->width, c->height);
if (!tmp_picture) {
fprintf(stderr, "Could not allocate temporary picture\n");
exit(1);
}
}
}
int got_packet_ptr = 0;
av_init_packet(&avpkt);
avpkt.data = outbuf;
avpkt.size = outbuf_size;
u_size = avcodec_encode_video2(c, &avpkt, m_pYUVFrame, &got_packet_ptr);
if (u_size == 0)
/* prepare a dummy image */
static void fill_yuv_image(AVFrame *pict, int frame_index, int width, int height)
{
fwrite(avpkt.data, 1, avpkt.size, f);
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;
}
}
fclose(f);
delete []m_pRGBFrame;
delete []m_pYUVFrame;
delete []rgb_buff;
free(outbuf);
avcodec_close(c);
av_free(c);
/* 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 out_size, ret;
AVCodecContext *c;
static struct SwsContext *img_convert_ctx;
c = st->codec;
if (frame_count >= STREAM_NB_FRAMES) {
/* no more frame to compress. The codec has a latency of a few
frames if using B frames, so we get the last frames by
passing the same picture again */
} else {
if (c->pix_fmt != PIX_FMT_YUV420P) {
/* as we only generate a YUV420P picture, we must convert it
to the codec pixel format if needed */
if (img_convert_ctx == NULL) {
img_convert_ctx = sws_getContext(c->width, c->height,
PIX_FMT_YUV420P,
c->width, c->height,
c->pix_fmt,
sws_flags, NULL, NULL, NULL);
if (img_convert_ctx == NULL) {
fprintf(stderr, "Cannot initialize the conversion context\n");
exit(1);
}
}
fill_yuv_image(tmp_picture, frame_count, c->width, c->height);
sws_scale(img_convert_ctx, tmp_picture->data, tmp_picture->linesize,
0, c->height, picture->data, picture->linesize);
} else {
fill_yuv_image(picture, frame_count, c->width, c->height);
}
}
if (oc->oformat->flags & AVFMT_RAWPICTURE) {
/* raw video case. The API will change slightly in the near
future for that. */
AVPacket pkt;
av_init_packet(&pkt);
pkt.flags |= AV_PKT_FLAG_KEY;
pkt.stream_index = st->index;
pkt.data = (uint8_t *)picture;
pkt.size = sizeof(AVPicture);
ret = av_interleaved_write_frame(oc, &pkt);
} else {
/* encode the image */
out_size = avcodec_encode_video(c, video_outbuf, video_outbuf_size, picture);
/* if zero size, it means the image was buffered */
if (out_size > 0) {
AVPacket pkt;
av_init_packet(&pkt);
if (c->coded_frame->pts != AV_NOPTS_VALUE)
pkt.pts= av_rescale_q(c->coded_frame->pts, c->time_base, st->time_base);
if(c->coded_frame->key_frame)
pkt.flags |= AV_PKT_FLAG_KEY;
pkt.stream_index = st->index;
pkt.data = video_outbuf;
pkt.size = out_size;
// printf("pts %d \n", c->coded_frame->pts);
/* write the compressed frame in the media file */
ret = av_interleaved_write_frame(oc, &pkt);
} else {
ret = 0;
}
}
if (ret != 0) {
fprintf(stderr, "Error while writing video frame\n");
exit(1);
}
frame_count++;
}
static void close_video(AVFormatContext *oc, AVStream *st)
{
avcodec_close(st->codec);
av_free(picture->data[0]);
av_free(picture);
if (tmp_picture) {
av_free(tmp_picture->data[0]);
av_free(tmp_picture);
}
av_free(video_outbuf);
}
/**************************************************************/
/* media file output */
int main(int argc, char **argv)
{
const char *filename;
AVOutputFormat *fmt;
AVFormatContext *oc;
AVStream *audio_st, *video_st;
double audio_pts, video_pts;
int i;
/* initialize libavcodec, and register all codecs and formats */
av_register_all();
#if 0
if (argc != 2) {
printf("usage: %s output_file\n"
"API example program to output a media file with libavformat.\n"
"The output format is automatically guessed according to the file extension.\n"
"Raw images can also be output by using '%%d' in the filename\n"
"\n", argv[0]);
return 1;
}
filename = argv[1];
#endif
//#define RTMP_STREAM
#ifdef RTMP_STREAM
filename = "rtmp://192.168.0.239/live/livestream";
#else
filename = "1.mp4";
#endif
/* allocate the output media context */
avformat_alloc_output_context2(&oc, NULL, NULL, filename);
if (!oc)
{
printf("Could not deduce output format from file extension: using MPEG.\n");
avformat_alloc_output_context2(&oc, NULL, /*"mpeg"*/"flv", filename);
}
if (!oc)
{
return 1;
}
// 强制指定 264 编码
oc->oformat->video_codec = CODEC_ID_H264;
oc->oformat->audio_codec = CODEC_ID_AAC;
fmt = oc->oformat;
/* add the audio and video streams using the default format codecs
and initialize the codecs */
video_st = NULL;
audio_st = NULL;
if (fmt->video_codec != CODEC_ID_NONE) {
video_st = add_video_stream(oc, fmt->video_codec);
}
if (fmt->audio_codec != CODEC_ID_NONE) {
audio_st = add_audio_stream(oc, fmt->audio_codec);
}
av_dump_format(oc, 0, filename, 1);
/* now that all the parameters are set, we can open the audio and
video codecs and allocate the necessary encode buffers */
if (video_st)
open_video(oc, video_st);
if (audio_st)
open_audio(oc, audio_st);
/* open the output file, if needed */
if (!(fmt->flags & AVFMT_NOFILE)) {
if (avio_open(&oc->pb, filename, AVIO_FLAG_WRITE) < 0) {
fprintf(stderr, "Could not open '%s'\n", filename);
return 1;
}
}
/* write the stream header, if any */
avformat_write_header(oc, NULL);
picture->pts = 0;
for(;;)
{
/* compute current audio and video time */
if (audio_st)
audio_pts = (double)audio_st->pts.val * audio_st->time_base.num / audio_st->time_base.den;
else
audio_pts = 0.0;
if (video_st)
video_pts = (double)video_st->pts.val * video_st->time_base.num / video_st->time_base.den;
else
video_pts = 0.0;
if ((!audio_st || audio_pts >= STREAM_DURATION) &&
(!video_st || video_pts >= STREAM_DURATION))
break;
/* write interleaved audio and video frames */
if (!video_st || (video_st && audio_st && audio_pts < video_pts)) {
write_audio_frame(oc, audio_st);
} else {
write_video_frame(oc, video_st);
picture->pts++;
}
}
/* write the trailer, if any. the trailer must be written
* before you close the CodecContexts open when you wrote the
* header; otherwise write_trailer may try to use memory that
* was freed on av_codec_close() */
av_write_trailer(oc);
/* close each codec */
if (video_st)
close_video(oc, video_st);
if (audio_st)
close_audio(oc, audio_st);
/* free the streams */
for(i = 0; i < oc->nb_streams; i++) {
av_freep(&oc->streams[i]->codec);
av_freep(&oc->streams[i]);
}
if (!(fmt->flags & AVFMT_NOFILE)) {
/* close the output file */
avio_close(oc->pb);
}
/* free the stream */
av_free(oc);
return 0;
}

Write Preview
Loading…
Cancel
Save