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extract_mvs.c

Read from input file, decode video stream and print a motion vectors representation to stdout.

Read from input file, decode video stream and print a motion vectors representation to stdout.

/*
* Copyright (c) 2012 Stefano Sabatini
* Copyright (c) 2014 Clément Bœsch
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
/**
* @file libavcodec motion vectors extraction API usage example
* @example extract_mvs.c
*
* Read from input file, decode video stream and print a motion vectors
* representation to stdout.
*/
#include <libavutil/motion_vector.h>
#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>
static AVFormatContext *fmt_ctx = NULL;
static AVCodecContext *video_dec_ctx = NULL;
static AVStream *video_stream = NULL;
static const char *src_filename = NULL;
static int video_stream_idx = -1;
static AVFrame *frame = NULL;
static int video_frame_count = 0;
static int decode_packet(const AVPacket *pkt)
{
int ret = avcodec_send_packet(video_dec_ctx, pkt);
if (ret < 0) {
fprintf(stderr, "Error while sending a packet to the decoder: %s\n", av_err2str(ret));
return ret;
}
while (ret >= 0) {
ret = avcodec_receive_frame(video_dec_ctx, frame);
if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF) {
break;
} else if (ret < 0) {
fprintf(stderr, "Error while receiving a frame from the decoder: %s\n", av_err2str(ret));
return ret;
}
if (ret >= 0) {
int i;
AVFrameSideData *sd;
video_frame_count++;
sd = av_frame_get_side_data(frame, AV_FRAME_DATA_MOTION_VECTORS);
if (sd) {
const AVMotionVector *mvs = (const AVMotionVector *)sd->data;
for (i = 0; i < sd->size / sizeof(*mvs); i++) {
const AVMotionVector *mv = &mvs[i];
printf("%d,%2d,%2d,%2d,%4d,%4d,%4d,%4d,0x%"PRIx64",%4d,%4d,%4d\n",
video_frame_count, mv->source,
mv->w, mv->h, mv->src_x, mv->src_y,
mv->dst_x, mv->dst_y, mv->flags,
mv->motion_x, mv->motion_y, mv->motion_scale);
}
}
av_frame_unref(frame);
}
}
return 0;
}
static int open_codec_context(AVFormatContext *fmt_ctx, enum AVMediaType type)
{
int ret;
AVStream *st;
AVCodecContext *dec_ctx = NULL;
const AVCodec *dec = NULL;
AVDictionary *opts = NULL;
ret = av_find_best_stream(fmt_ctx, type, -1, -1, &dec, 0);
if (ret < 0) {
fprintf(stderr, "Could not find %s stream in input file '%s'\n",
av_get_media_type_string(type), src_filename);
return ret;
} else {
int stream_idx = ret;
st = fmt_ctx->streams[stream_idx];
dec_ctx = avcodec_alloc_context3(dec);
if (!dec_ctx) {
fprintf(stderr, "Failed to allocate codec\n");
return AVERROR(EINVAL);
}
ret = avcodec_parameters_to_context(dec_ctx, st->codecpar);
if (ret < 0) {
fprintf(stderr, "Failed to copy codec parameters to codec context\n");
avcodec_free_context(&dec_ctx);
return ret;
}
/* Init the video decoder */
av_dict_set(&opts, "flags2", "+export_mvs", 0);
ret = avcodec_open2(dec_ctx, dec, &opts);
av_dict_free(&opts);
if (ret < 0) {
fprintf(stderr, "Failed to open %s codec\n",
av_get_media_type_string(type));
return ret;
}
video_stream_idx = stream_idx;
video_stream = fmt_ctx->streams[video_stream_idx];
video_dec_ctx = dec_ctx;
}
return 0;
}
int main(int argc, char **argv)
{
int ret = 0;
AVPacket *pkt = NULL;
if (argc != 2) {
fprintf(stderr, "Usage: %s <video>\n", argv[0]);
exit(1);
}
src_filename = argv[1];
if (avformat_open_input(&fmt_ctx, src_filename, NULL, NULL) < 0) {
fprintf(stderr, "Could not open source file %s\n", src_filename);
exit(1);
}
if (avformat_find_stream_info(fmt_ctx, NULL) < 0) {
fprintf(stderr, "Could not find stream information\n");
exit(1);
}
open_codec_context(fmt_ctx, AVMEDIA_TYPE_VIDEO);
av_dump_format(fmt_ctx, 0, src_filename, 0);
if (!video_stream) {
fprintf(stderr, "Could not find video stream in the input, aborting\n");
ret = 1;
goto end;
}
frame = av_frame_alloc();
if (!frame) {
fprintf(stderr, "Could not allocate frame\n");
ret = AVERROR(ENOMEM);
goto end;
}
pkt = av_packet_alloc();
if (!pkt) {
fprintf(stderr, "Could not allocate AVPacket\n");
ret = AVERROR(ENOMEM);
goto end;
}
printf("framenum,source,blockw,blockh,srcx,srcy,dstx,dsty,flags,motion_x,motion_y,motion_scale\n");
/* read frames from the file */
while (av_read_frame(fmt_ctx, pkt) >= 0) {
if (pkt->stream_index == video_stream_idx)
ret = decode_packet(pkt);
av_packet_unref(pkt);
if (ret < 0)
break;
}
/* flush cached frames */
decode_packet(NULL);
end:
avcodec_free_context(&video_dec_ctx);
avformat_close_input(&fmt_ctx);
av_frame_free(&frame);
av_packet_free(&pkt);
return ret < 0;
}
avcodec.h
Libavcodec external API header.
avformat.h
Main libavformat public API header.
main
int main(int argc, char *argv[])
Definition avio_list_dir.c:119
fmt_ctx
static AVFormatContext * fmt_ctx
Definition decode_filter_audio.c:44
dec_ctx
static AVCodecContext * dec_ctx
Definition decode_filter_audio.c:45
video_dec_ctx
static AVCodecContext * video_dec_ctx
Definition demux_decode.c:39
pkt
static AVPacket * pkt
Definition demux_decode.c:55
video_stream
static AVStream * video_stream
Definition demux_decode.c:42
decode_packet
static int decode_packet(AVCodecContext *dec, const AVPacket *pkt)
Definition demux_decode.c:110
open_codec_context
static int open_codec_context(int *stream_idx, AVCodecContext **dec_ctx, AVFormatContext *fmt_ctx, enum AVMediaType type)
Definition demux_decode.c:146
video_frame_count
static int video_frame_count
Definition demux_decode.c:56
src_filename
static const char * src_filename
Definition demux_decode.c:43
frame
static AVFrame * frame
Definition demux_decode.c:54
video_stream_idx
static int video_stream_idx
Definition demux_decode.c:53
avcodec_open2
int avcodec_open2(AVCodecContext *avctx, const AVCodec *codec, AVDictionary **options)
Initialize the AVCodecContext to use the given AVCodec.
avcodec_alloc_context3
AVCodecContext * avcodec_alloc_context3(const AVCodec *codec)
Allocate an AVCodecContext and set its fields to default values.
avcodec_parameters_to_context
int avcodec_parameters_to_context(AVCodecContext *codec, const struct AVCodecParameters *par)
Fill the codec context based on the values from the supplied codec parameters.
avcodec_free_context
void avcodec_free_context(AVCodecContext **avctx)
Free the codec context and everything associated with it and write NULL to the provided pointer.
avcodec_receive_frame
int avcodec_receive_frame(AVCodecContext *avctx, AVFrame *frame)
Alias for avcodec_receive_frame_flags(avctx, frame, 0).
avcodec_send_packet
int avcodec_send_packet(AVCodecContext *avctx, const AVPacket *avpkt)
Supply raw packet data as input to a decoder.
av_packet_free
void av_packet_free(AVPacket **pkt)
Free the packet, if the packet is reference counted, it will be unreferenced first.
av_packet_unref
void av_packet_unref(AVPacket *pkt)
Wipe the packet.
av_packet_alloc
AVPacket * av_packet_alloc(void)
Allocate an AVPacket and set its fields to default values.
av_read_frame
int av_read_frame(AVFormatContext *s, AVPacket *pkt)
Return the next frame of a stream.
av_find_best_stream
int av_find_best_stream(AVFormatContext *ic, enum AVMediaType type, int wanted_stream_nb, int related_stream, const struct AVCodec **decoder_ret, int flags)
Find the "best" stream in the file.
avformat_open_input
int avformat_open_input(AVFormatContext **ps, const char *url, const AVInputFormat *fmt, AVDictionary **options)
Open an input stream and read the header.
avformat_find_stream_info
int avformat_find_stream_info(AVFormatContext *ic, AVDictionary **options)
Read packets of a media file to get stream information.
avformat_close_input
void avformat_close_input(AVFormatContext **s)
Close an opened input AVFormatContext.
av_dump_format
void av_dump_format(AVFormatContext *ic, int index, const char *url, int is_output)
Print detailed information about the input or output format, such as duration, bitrate,...
av_dict_free
void av_dict_free(AVDictionary **m)
Free all the memory allocated for an AVDictionary struct and all keys and values.
AVDictionary
struct AVDictionary AVDictionary
Definition dict.h:95
av_dict_set
int av_dict_set(AVDictionary **pm, const char *key, const char *value, int flags)
Set the given entry in *pm, overwriting an existing entry.
AVERROR_EOF
#define AVERROR_EOF
End of file.
Definition error.h:57
av_err2str
#define av_err2str(errnum)
Convenience macro, the return value should be used only directly in function arguments but never stan...
Definition error.h:122
AVERROR
#define AVERROR(e)
Definition error.h:45
av_frame_unref
void av_frame_unref(AVFrame *frame)
Unreference all the buffers referenced by frame and reset the frame fields.
av_frame_get_side_data
AVFrameSideData * av_frame_get_side_data(const AVFrame *frame, enum AVFrameSideDataType type)
av_frame_free
void av_frame_free(AVFrame **frame)
Free the frame and any dynamically allocated objects in it, e.g.
av_frame_alloc
AVFrame * av_frame_alloc(void)
Allocate an AVFrame and set its fields to default values.
AV_FRAME_DATA_MOTION_VECTORS
@ AV_FRAME_DATA_MOTION_VECTORS
Motion vectors exported by some codecs (on demand through the export_mvs flag set in the libavcodec A...
Definition frame.h:97
av_get_media_type_string
const char * av_get_media_type_string(enum AVMediaType media_type)
Return a string describing the media_type enum, NULL if media_type is unknown.
AVMediaType
AVMediaType
Definition avutil.h:198
AVMEDIA_TYPE_VIDEO
@ AVMEDIA_TYPE_VIDEO
Definition avutil.h:200
motion_vector.h
AVCodecContext
main external API structure.
Definition avcodec.h:439
AVCodec
AVCodec.
Definition codec.h:172
AVFormatContext
Format I/O context.
Definition avformat.h:1263
AVFrameSideData
Structure to hold side data for an AVFrame.
Definition frame.h:282
AVFrameSideData::size
size_t size
Definition frame.h:285
AVFrameSideData::data
uint8_t * data
Definition frame.h:284
AVFrame
This structure describes decoded (raw) audio or video data.
Definition frame.h:427
AVMotionVector
Definition motion_vector.h:24
AVMotionVector::source
int32_t source
Where the current macroblock comes from; negative value when it comes from the past,...
Definition motion_vector.h:30
AVMotionVector::src_y
int16_t src_y
Definition motion_vector.h:38
AVMotionVector::motion_y
int32_t motion_y
Definition motion_vector.h:53
AVMotionVector::dst_x
int16_t dst_x
Absolute destination position.
Definition motion_vector.h:42
AVMotionVector::flags
uint64_t flags
Extra flag information.
Definition motion_vector.h:47
AVMotionVector::motion_scale
uint16_t motion_scale
Definition motion_vector.h:54
AVMotionVector::h
uint8_t h
Definition motion_vector.h:34
AVMotionVector::motion_x
int32_t motion_x
Motion vector src_x = dst_x + motion_x / motion_scale src_y = dst_y + motion_y / motion_scale.
Definition motion_vector.h:53
AVMotionVector::w
uint8_t w
Width and height of the block.
Definition motion_vector.h:34
AVMotionVector::src_x
int16_t src_x
Absolute source position.
Definition motion_vector.h:38
AVMotionVector::dst_y
int16_t dst_y
Definition motion_vector.h:42
AVPacket
This structure stores compressed data.
Definition packet.h:565
AVStream
Stream structure.
Definition avformat.h:744
AVStream::codecpar
AVCodecParameters * codecpar
Codec parameters associated with this stream.
Definition avformat.h:767