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output example: use a struct to bundle the video stream variables together

tags/n2.3
Anton Khirnov 11 years ago
parent
38d044429d
commit
294daf71a7
1 changed files with 50 additions and 43 deletions
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  1. +50
    -43
      doc/examples/output.c

+ 50
- 43
doc/examples/output.c View File

@@ -46,6 +46,14 @@

static int sws_flags = SWS_BICUBIC;

// a wrapper around a single output AVStream
typedef struct OutputStream {
AVStream *st;

AVFrame *frame;
AVFrame *tmp_frame;
} OutputStream;

/**************************************************************/
/* audio output */

@@ -176,14 +184,13 @@ static void close_audio(AVFormatContext *oc, AVStream *st)
/**************************************************************/
/* video output */

static AVFrame *picture, *tmp_picture;
static int frame_count;

/* Add a video output stream. */
static AVStream *add_video_stream(AVFormatContext *oc, enum AVCodecID codec_id)
static void add_video_stream(OutputStream *ost, AVFormatContext *oc,
enum AVCodecID codec_id)
{
AVCodecContext *c;
AVStream *st;
AVCodec *codec;

/* find the video encoder */
@@ -193,13 +200,13 @@ static AVStream *add_video_stream(AVFormatContext *oc, enum AVCodecID codec_id)
exit(1);
}

st = avformat_new_stream(oc, codec);
if (!st) {
ost->st = avformat_new_stream(oc, codec);
if (!ost->st) {
fprintf(stderr, "Could not alloc stream\n");
exit(1);
}

c = st->codec;
c = ost->st->codec;

/* Put sample parameters. */
c->bit_rate = 400000;
@@ -227,8 +234,6 @@ static AVStream *add_video_stream(AVFormatContext *oc, enum AVCodecID codec_id)
/* 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 AVPixelFormat pix_fmt, int width, int height)
@@ -254,11 +259,11 @@ static AVFrame *alloc_picture(enum AVPixelFormat pix_fmt, int width, int height)
return picture;
}

static void open_video(AVFormatContext *oc, AVStream *st)
static void open_video(AVFormatContext *oc, OutputStream *ost)
{
AVCodecContext *c;

c = st->codec;
c = ost->st->codec;

/* open the codec */
if (avcodec_open2(c, NULL, NULL) < 0) {
@@ -267,8 +272,8 @@ static void open_video(AVFormatContext *oc, AVStream *st)
}

/* Allocate the encoded raw picture. */
picture = alloc_picture(c->pix_fmt, c->width, c->height);
if (!picture) {
ost->frame = alloc_picture(c->pix_fmt, c->width, c->height);
if (!ost->frame) {
fprintf(stderr, "Could not allocate picture\n");
exit(1);
}
@@ -276,10 +281,10 @@ static void open_video(AVFormatContext *oc, AVStream *st)
/* 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;
ost->tmp_frame = NULL;
if (c->pix_fmt != AV_PIX_FMT_YUV420P) {
tmp_picture = alloc_picture(AV_PIX_FMT_YUV420P, c->width, c->height);
if (!tmp_picture) {
ost->tmp_frame = alloc_picture(AV_PIX_FMT_YUV420P, c->width, c->height);
if (!ost->tmp_frame) {
fprintf(stderr, "Could not allocate temporary picture\n");
exit(1);
}
@@ -316,13 +321,13 @@ static void fill_yuv_image(AVFrame *pict, int frame_index,
}
}

static void write_video_frame(AVFormatContext *oc, AVStream *st)
static void write_video_frame(AVFormatContext *oc, OutputStream *ost)
{
int ret;
AVCodecContext *c;
static struct SwsContext *img_convert_ctx;

c = st->codec;
c = ost->st->codec;

if (frame_count >= STREAM_NB_FRAMES) {
/* No more frames to compress. The codec has a latency of a few
@@ -344,11 +349,11 @@ static void write_video_frame(AVFormatContext *oc, AVStream *st)
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);
fill_yuv_image(ost->tmp_frame, frame_count, c->width, c->height);
sws_scale(img_convert_ctx, ost->tmp_frame->data, ost->tmp_frame->linesize,
0, c->height, ost->frame->data, ost->frame->linesize);
} else {
fill_yuv_image(picture, frame_count, c->width, c->height);
fill_yuv_image(ost->frame, frame_count, c->width, c->height);
}
}

@@ -359,8 +364,8 @@ static void write_video_frame(AVFormatContext *oc, AVStream *st)
av_init_packet(&pkt);

pkt.flags |= AV_PKT_FLAG_KEY;
pkt.stream_index = st->index;
pkt.data = (uint8_t *)picture;
pkt.stream_index = ost->st->index;
pkt.data = (uint8_t *)ost->frame;
pkt.size = sizeof(AVPicture);

ret = av_interleaved_write_frame(oc, &pkt);
@@ -370,11 +375,11 @@ static void write_video_frame(AVFormatContext *oc, AVStream *st)
av_init_packet(&pkt);

/* encode the image */
ret = avcodec_encode_video2(c, &pkt, picture, &got_packet);
ret = avcodec_encode_video2(c, &pkt, ost->frame, &got_packet);
/* If size is zero, it means the image was buffered. */
if (!ret && got_packet && pkt.size) {
av_packet_rescale_ts(&pkt, c->time_base, st->time_base);
pkt.stream_index = st->index;
av_packet_rescale_ts(&pkt, c->time_base, ost->st->time_base);
pkt.stream_index = ost->st->index;

/* Write the compressed frame to the media file. */
ret = av_interleaved_write_frame(oc, &pkt);
@@ -389,11 +394,11 @@ static void write_video_frame(AVFormatContext *oc, AVStream *st)
frame_count++;
}

static void close_video(AVFormatContext *oc, AVStream *st)
static void close_video(AVFormatContext *oc, OutputStream *ost)
{
avcodec_close(st->codec);
av_frame_free(&picture);
av_frame_free(&tmp_picture);
avcodec_close(ost->st->codec);
av_frame_free(&ost->frame);
av_frame_free(&ost->tmp_frame);
}

/**************************************************************/
@@ -401,11 +406,13 @@ static void close_video(AVFormatContext *oc, AVStream *st)

int main(int argc, char **argv)
{
OutputStream video_st;
const char *filename;
AVOutputFormat *fmt;
AVFormatContext *oc;
AVStream *audio_st, *video_st;
AVStream *audio_st;
double audio_pts, video_pts;
int have_video = 0;
int i;

/* Initialize libavcodec, and register all codecs and formats. */
@@ -444,10 +451,10 @@ int main(int argc, char **argv)

/* 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 != AV_CODEC_ID_NONE) {
video_st = add_video_stream(oc, fmt->video_codec);
add_video_stream(&video_st, oc, fmt->video_codec);
have_video = 1;
}
if (fmt->audio_codec != AV_CODEC_ID_NONE) {
audio_st = add_audio_stream(oc, fmt->audio_codec);
@@ -455,8 +462,8 @@ int main(int argc, char **argv)

/* 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 (have_video)
open_video(oc, &video_st);
if (audio_st)
open_audio(oc, audio_st);

@@ -480,21 +487,21 @@ int main(int argc, char **argv)
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;
if (have_video)
video_pts = (double)video_st.st->pts.val * video_st.st->time_base.num /
video_st.st->time_base.den;
else
video_pts = 0.0;

if ((!audio_st || audio_pts >= STREAM_DURATION) &&
(!video_st || video_pts >= STREAM_DURATION))
(!have_video || video_pts >= STREAM_DURATION))
break;

/* write interleaved audio and video frames */
if (!video_st || (video_st && audio_st && audio_pts < video_pts)) {
if (!have_video || (have_video && audio_st && audio_pts < video_pts)) {
write_audio_frame(oc, audio_st);
} else {
write_video_frame(oc, video_st);
write_video_frame(oc, &video_st);
}
}

@@ -505,8 +512,8 @@ int main(int argc, char **argv)
av_write_trailer(oc);

/* Close each codec. */
if (video_st)
close_video(oc, video_st);
if (have_video)
close_video(oc, &video_st);
if (audio_st)
close_audio(oc, audio_st);



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