[FFmpeg-devel] [PATCH 19/21] doc/examples/extract_timed_metadata: added a bare-bones metadata extractor; find only the frames
Michael Niedermayer
michael at niedermayer.cc
Tue Aug 23 17:29:13 EEST 2016
On Tue, Aug 23, 2016 at 12:03:37PM +0300, erkki.seppala.ext at nokia.com wrote:
> From: Erkki Seppälä <erkki.seppala.ext at nokia.com>
>
> Signed-off-by: Erkki Seppälä <erkki.seppala.ext at nokia.com>
> Signed-off-by: OZOPlayer <OZOPL at nokia.com>
> ---
> doc/examples/Makefile | 1 +
> doc/examples/extract_timed_metadata.c | 233 ++++++++++++++++++++++++++++++++++
> 2 files changed, 234 insertions(+)
> create mode 100644 doc/examples/extract_timed_metadata.c
>
> diff --git a/doc/examples/Makefile b/doc/examples/Makefile
> index af38159..c10033e 100644
> --- a/doc/examples/Makefile
> +++ b/doc/examples/Makefile
> @@ -16,6 +16,7 @@ EXAMPLES= avio_dir_cmd \
> decoding_encoding \
> demuxing_decoding \
> extract_mvs \
> + extract_timed_metadata \
> filtering_video \
> filtering_audio \
> http_multiclient \
> diff --git a/doc/examples/extract_timed_metadata.c b/doc/examples/extract_timed_metadata.c
> new file mode 100644
> index 0000000..ef84ed9
> --- /dev/null
> +++ b/doc/examples/extract_timed_metadata.c
> @@ -0,0 +1,233 @@
> +/*
> + * Copyright (c) 2010 Nicolas George
> + * Copyright (c) 2011 Stefano Sabatini
> + * Copyright (c) 2015 Erkki Seppälä <erkki.seppala.ext at nokia.com>
> + *
> + * 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
> + * API example for decoding and filtering
> + * @example filtering_video.c
> + */
> +
> +#define _XOPEN_SOURCE 600 /* for usleep */
> +#include <unistd.h>
> +#include <stdint.h>
> +
> +#include <libavcodec/avcodec.h>
> +#include <libavformat/avformat.h>
> +#include <libavutil/opt.h>
> +#include <assert.h>
> +#include <ctype.h>
> +
> +#define MAX_METADATA_STREAMS 10
> +
> +static AVFormatContext *fmt_ctx;
> +static AVCodecContext *dec_ctx[MAX_METADATA_STREAMS];
> +static int metadata_stream_indices[MAX_METADATA_STREAMS + 1] = { -1 }; /* terminated with -1 */
> +
> +static int open_input_file(const char *filename)
> +{
> + int ret;
> + AVCodec *dec = avcodec_find_decoder(AV_CODEC_ID_META);
> + int i;
> + int nb_metadata = 0;
> +
> + if ((ret = avformat_open_input(&fmt_ctx, filename, NULL, NULL)) < 0) {
> + av_log(NULL, AV_LOG_ERROR, "Cannot open input file\n");
> + return ret;
> + }
> +
> + if ((ret = avformat_find_stream_info(fmt_ctx, NULL)) < 0) {
> + av_log(NULL, AV_LOG_ERROR, "Cannot find stream information\n");
> + return ret;
> + }
> +
> + for (i = 0; i < fmt_ctx->nb_streams; i++) {
> + if (fmt_ctx->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_DATA) {
> + assert(nb_metadata < MAX_METADATA_STREAMS);
> + metadata_stream_indices[nb_metadata] = i;
> + nb_metadata++;
> + }
> + }
> + metadata_stream_indices[nb_metadata] = -1;
> +
> + if (nb_metadata == 0) {
> + av_log(NULL, AV_LOG_ERROR, "Cannot find a video stream in the input file\n");
> + return ret;
> + }
> +
> + for (i = 0; i < nb_metadata; i++) {
> + dec_ctx[i] = avcodec_alloc_context3(dec);
> + if ((ret = avcodec_open2(dec_ctx[i], dec, NULL)) < 0) {
> + av_log(NULL, AV_LOG_ERROR, "Cannot open metadata decoder for metadata stream on track %d\n", i);
> + return ret;
> + }
> + }
> +
> + return 0;
> +}
> +
> +static void* memndup(void* ptr, int n)
> +{
> + void* buffer = malloc(n);
> + memcpy(buffer, ptr, n);
> + return buffer;
> +}
> +
> +static char* local_strndup(char* str, int n)
> +{
> + int len = strlen(str);
> + if (len > n) {
> + len = n;
> + }
> + char* buffer = malloc(n + 1);
> + memcpy(buffer, str, n);
> + buffer[len] = 0;
> + return buffer;
> +}
> +
> +int main(int argc, char **argv)
> +{
> + int ret;
> + AVPacket packet;
> + AVData *metadata = avdata_alloc();
> + int got_frame;
> + int i;
> +
> + if (!metadata) {
> + perror("Could not allocate metadata");
> + exit(1);
> + }
> + if (argc != 2) {
> + fprintf(stderr, "Usage: %s file\n", argv[0]);
> + exit(1);
> + }
> +
> + av_register_all();
> +
> + if ((ret = open_input_file(argv[1])) < 0)
> + goto end;
> +
> + for (i = 0; metadata_stream_indices[i] >= 0; i++) {
> + char *uri = NULL;
> + int nb_src_idxs;
> + int *src_idxs = NULL;
> + char *tref_tag = NULL;
> + int size;
> + int trefsSize;
> + AVTimedMetadata* metadata =
> + (AVTimedMetadata*) av_stream_get_side_data(fmt_ctx->streams[metadata_stream_indices[i]],
> + AV_PKT_DATA_TIMED_METADATA_INFO,
> + &size);
> + AVTrackReferences* trefs =
> + (AVTrackReferences*) av_stream_get_side_data(fmt_ctx->streams[metadata_stream_indices[i]],
> + AV_PKT_DATA_TRACK_REFERENCES,
> + &trefsSize);
> + if (metadata) {
> + tref_tag = local_strndup(metadata->meta_tag, 4);
> + uri = local_strndup((char*) (metadata + 1), metadata->meta_length);
> + int j;
> + int conf_len = metadata->conf_length;
> + void* conf = memndup((char*) (metadata + 1) + metadata->meta_length, metadata->conf_length);
> + char* conf_tag = local_strndup(metadata->conf_tag, 4);
> + nb_src_idxs = trefs ? trefs->nb_tracks : 0;
> + src_idxs = (int*) (trefs + 1);
> + printf("Track #%d describing track%s with tref %s",
> + metadata_stream_indices[i] + 1,
> + nb_src_idxs > 1 ? "s" : "",
> + tref_tag);
> + for (j = 0; j < nb_src_idxs; j++)
> + printf(" #%d", src_idxs[j]);
> + printf(" url: %s \n", uri);
> + printf(" configuration conf tag %s, %d bytes:", conf_tag, conf_len);
> + for (j = 0; j < conf_len; ++j) {
> + unsigned char ch = ((unsigned char*) conf)[j];
> + if (isprint(ch)) {
> + printf(" %c", ch);
> + } else {
> + printf(" %2x", ((unsigned char*) conf)[j]);
> + }
> + }
> + printf("\n");
> + free(conf);
> + free(conf_tag);
> + free(uri);
> + free(tref_tag);
> + } else {
> + printf("No meta data info for track %d?!\n", metadata_stream_indices[i]);
> + }
> + }
> +
> + /* read all packets */
> + while (1) {
> + if ((ret = av_read_frame(fmt_ctx, &packet)) < 0)
> + break;
> +
> + for (i = 0; metadata_stream_indices[i] >= 0; i++) {
> + if (packet.stream_index == metadata_stream_indices[i]) {
> + got_frame = 0;
> +
> + ret = dec_ctx[i]->codec->decode(dec_ctx[i], metadata, &got_frame, &packet);
use of private libavcodec API is not allowed by external applications
like an example would be
see avcodec.h:
/*****************************************************************
* No fields below this line are part of the public API. They
* may not be used outside of libavcodec and can be changed and
* removed at will.
* New public fields should be added right above.
*****************************************************************
[...]
--
Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
When you are offended at any man's fault, turn to yourself and study your
own failings. Then you will forget your anger. -- Epictetus
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