http://blog.csdn.net/eightdegree/article/details/7425811
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。
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 */
-
-
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;
-
-
st = avformat_new_stream(oc, NULL);
-
if
(!st) {
-
fprintf(stderr,
“Could not alloc stream\n”
);
-
exit(1);
-
}
-
st->id = 1;
-
-
c = st->codec;
-
c->codec_id = codec_id;
-
c->codec_type = AVMEDIA_TYPE_AUDIO;
-
-
/* put sample parameters */
-
c->sample_fmt = AV_SAMPLE_FMT_S16;
-
c->bit_rate = 64000;
-
c->sample_rate = 44100;
-
c->channels = 2;
-
-
// some formats want stream headers to be separate
-
if
(oc->oformat->flags & AVFMT_GLOBALHEADER)
-
c->flags |= CODEC_FLAG_GLOBAL_HEADER;
-
-
return
st;
-
}
-
-
static
void
open_audio(AVFormatContext *oc, AVStream *st)
-
{
-
AVCodecContext *c;
-
AVCodec *codec;
-
-
c = st->codec;
-
-
/* find the audio encoder */
-
codec = avcodec_find_encoder(c->codec_id);
-
if
(!codec) {
-
fprintf(stderr,
“codec not found\n”
);
-
exit(1);
-
}
-
-
/* open it */
-
if
(avcodec_open(c, codec) < 0) {
-
fprintf(stderr,
“could not open codec\n”
);
-
exit(1);
-
}
-
-
/* 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);
-
}
-
-
/* 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;
-
}
-
}
-
-
static
void
write_audio_frame(AVFormatContext *oc, AVStream *st)
-
{
-
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);
-
}
-
-
/**************************************************************/
-
/* 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)
-
{
-
AVCodecContext *c;
-
AVStream *st;
-
AVCodec *codec;
-
-
st = avformat_new_stream(oc, NULL);
-
if
(!st) {
-
fprintf(stderr,
“Could not alloc stream\n”
);
-
exit(1);
-
}
-
-
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;
-
-
-
-
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;
-
}
-
-
static
void
open_video(AVFormatContext *oc, AVStream *st)
-
{
-
AVCodec *codec;
-
AVCodecContext *c;
-
-
c = st->codec;
-
-
/* find the video encoder */
-
codec = avcodec_find_encoder(c->codec_id);
-
if
(!codec) {
-
fprintf(stderr,
“codec not found\n”
);
-
exit(1);
-
}
-
-
/* open the codec */
-
if
(avcodec_open(c, codec) < 0) {
-
fprintf(stderr,
“could not open codec\n”
);
-
exit(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);
-
}
-
-
/* 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);
-
}
-
}
-
}
-
-
/* prepare a dummy image */
-
static
void
fill_yuv_image(AVFrame *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
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;
-
}