[FFmpeg-devel] [PATCH] Add example reencoding_filtered_video.c
Nicolas George
george at nsup.org
Thu Jan 30 14:40:54 CET 2014
Le primidi 11 pluviôse, an CCXXII, Andrey Utkin a écrit :
> ---
> configure | 2 +
> doc/Makefile | 1 +
> doc/examples/Makefile | 3 +-
> doc/examples/reencoding_filtered_video.c | 335 +++++++++++++++++++++++++++++++
> 4 files changed, 340 insertions(+), 1 deletion(-)
> create mode 100644 doc/examples/reencoding_filtered_video.c
>
> diff --git a/configure b/configure
> index 0fbaa6a..40dab3d 100755
> --- a/configure
> +++ b/configure
> @@ -1247,6 +1247,7 @@ EXAMPLE_LIST="
> filtering_video_example
> metadata_example
> muxing_example
> + reencoding_filtered_video_example
> remuxing_example
> resampling_audio_example
> scaling_video_example
> @@ -2396,6 +2397,7 @@ filtering_audio_example_deps="avfilter avcodec avformat avutil"
> filtering_video_example_deps="avfilter avcodec avformat avutil"
> metadata_example_deps="avformat avutil"
> muxing_example_deps="avcodec avformat avutil swscale"
> +reencoding_filtered_video_example_deps="avfilter avcodec avformat avutil"
> remuxing_example_deps="avcodec avformat avutil"
> resampling_audio_example_deps="avutil swresample"
> scaling_video_example_deps="avutil swscale"
> diff --git a/doc/Makefile b/doc/Makefile
> index 4092f52..f6cd2d8 100644
> --- a/doc/Makefile
> +++ b/doc/Makefile
> @@ -42,6 +42,7 @@ DOC_EXAMPLES-$(CONFIG_FILTERING_AUDIO_EXAMPLE) += filtering_audio
> DOC_EXAMPLES-$(CONFIG_FILTERING_VIDEO_EXAMPLE) += filtering_video
> DOC_EXAMPLES-$(CONFIG_METADATA_EXAMPLE) += metadata
> DOC_EXAMPLES-$(CONFIG_MUXING_EXAMPLE) += muxing
> +DOC_EXAMPLES-$(CONFIG_REENCODING_FILTERED_VIDEO_EXAMPLE) += reencoding_filtered_video
> DOC_EXAMPLES-$(CONFIG_REMUXING_EXAMPLE) += remuxing
> DOC_EXAMPLES-$(CONFIG_RESAMPLING_AUDIO_EXAMPLE) += resampling_audio
> DOC_EXAMPLES-$(CONFIG_SCALING_VIDEO_EXAMPLE) += scaling_video
> diff --git a/doc/examples/Makefile b/doc/examples/Makefile
> index a25455e..15c44d2 100644
> --- a/doc/examples/Makefile
> +++ b/doc/examples/Makefile
> @@ -7,7 +7,7 @@ FFMPEG_LIBS= libavdevice \
> libswscale \
> libavutil \
>
> -CFLAGS += -Wall -g
> +CFLAGS += -Wall -g -O0 -ggdb
Looks unrelated.
> CFLAGS := $(shell pkg-config --cflags $(FFMPEG_LIBS)) $(CFLAGS)
> LDLIBS := $(shell pkg-config --libs $(FFMPEG_LIBS)) $(LDLIBS)
>
> @@ -17,6 +17,7 @@ EXAMPLES= decoding_encoding \
> filtering_audio \
> metadata \
> muxing \
> + reencoding_filtered_video \
> remuxing \
> resampling_audio \
> scaling_video \
> diff --git a/doc/examples/reencoding_filtered_video.c b/doc/examples/reencoding_filtered_video.c
> new file mode 100644
> index 0000000..44fc5ff
> --- /dev/null
> +++ b/doc/examples/reencoding_filtered_video.c
> @@ -0,0 +1,335 @@
> +/*
> + * Copyright (c) 2010 Nicolas George
> + * Copyright (c) 2011 Stefano Sabatini
> + * Copyright (c) 2014 Andrey Utkin
> + *
> + * 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 demuxing, decoding, filtering, encoding and muxing
> + * @example doc/examples/reencoding_filtered_video.c
> + */
> +
> +#include <unistd.h>
> +
> +#include <libavcodec/avcodec.h>
> +#include <libavformat/avformat.h>
> +#include <libavfilter/avfiltergraph.h>
> +#include <libavfilter/avcodec.h>
> +#include <libavfilter/buffersink.h>
> +#include <libavfilter/buffersrc.h>
> +#include <libavutil/opt.h>
> +
> +/* Filtergraph string is a good place to set up resize, pixel format
> + * conversion, constant output fps etc.
> + * In this example, filtering pipeline just passes input frames unchanged.
> + * By utilizing filtering, you get video pixel format (or audio sample format)
> + * conversion between input-provided one to chosen output-supported one, for
> + * free - it happens automatically.
> + */
> +const char *filter_descr = "null";
> +
> +static AVFormatContext *ifmt_ctx;
> +static AVFormatContext *ofmt_ctx;
> +static AVCodecContext *dec_ctx;
> +static AVCodecContext *enc_ctx;
> +AVFilterContext *buffersink_ctx;
> +AVFilterContext *buffersrc_ctx;
> +AVFilterGraph *filter_graph;
> +static int video_stream_index = -1;
> +
> +static int open_input_file(const char *filename)
> +{
> + int ret;
> +
> + if ((ret = avformat_open_input(&ifmt_ctx, filename, NULL, NULL)) < 0) {
> + av_log(NULL, AV_LOG_ERROR, "Cannot open input file\n");
> + return ret;
> + }
> +
> + if ((ret = avformat_find_stream_info(ifmt_ctx, NULL)) < 0) {
> + av_log(NULL, AV_LOG_ERROR, "Cannot find stream information\n");
> + return ret;
> + }
> +
> + /* select the video stream */
> + ret = av_find_best_stream(ifmt_ctx, AVMEDIA_TYPE_VIDEO, -1, -1, NULL, 0);
> + if (ret < 0) {
> + av_log(NULL, AV_LOG_ERROR, "Cannot find a video stream in the input file\n");
> + return ret;
> + }
> + video_stream_index = ret;
> + dec_ctx = ifmt_ctx->streams[video_stream_index]->codec;
> + av_opt_set_int(dec_ctx, "refcounted_frames", 1, 0);
Maybe add a comment to explain why it is useful.
> +
> + av_dump_format(ifmt_ctx, 0, filename, 0);
> + return 0;
> +}
> +
> +static int open_output_file(const char *filename)
> +{
> + AVStream *out_stream;
> + AVCodec *enc;
> + AVDictionary *encoder_opts = NULL;
> + int ret;
> +
> + avformat_alloc_output_context2(&ofmt_ctx, NULL, NULL, filename);
ofmt_ctx needs to be NULL before that call. It is true because it is a
static global, but it is not explicit. I would suggest to add ofmt_ctx=NULL
just before, even though it is not used.
> + if (!ofmt_ctx) {
> + fprintf(stderr, "Could not create output context\n");
> + ret = AVERROR_UNKNOWN;
> + return ret;
> + }
> +
> + /* Open just one elementary stream for transcoded video */
> + enc = avcodec_find_encoder(AV_CODEC_ID_H264);
> +
> + out_stream = avformat_new_stream(ofmt_ctx, enc);
> + if (!out_stream) {
> + fprintf(stderr, "Failed allocating output stream\n");
> + ret = AVERROR_UNKNOWN;
> + return ret;
> + }
> +
> + if (ofmt_ctx->oformat->flags & AVFMT_GLOBALHEADER)
> + out_stream->codec->flags |= CODEC_FLAG_GLOBAL_HEADER;
> +
> + /* rewrite output codec setting according to our needs */
> + /* in this example, we choose transcoding to H264 */
> +
> + /* init the video decoder */
> + if ((ret = avcodec_open2(dec_ctx, avcodec_find_decoder(dec_ctx->codec_id), NULL)) < 0) {
> + av_log(NULL, AV_LOG_ERROR, "Cannot open video decoder\n");
> + return ret;
> + }
> +
> + /* init the video encoder */
> + enc_ctx = out_stream->codec;
> + enc_ctx->height = dec_ctx->height;
> + enc_ctx->width = dec_ctx->width;
> + /* yuv420p is just common in use and known to be supported by libx264
> + * pix_fmt can be also taken from enc->pix_fmts[]
> + */
> + enc_ctx->pix_fmt = AV_PIX_FMT_YUV420P;
> + enc_ctx->time_base = out_stream->time_base;
> + av_dict_set(&encoder_opts, "b", "100000", 0); /* set bitrate if needed */
For single pass encoding to file, "crf" would be more appropriate.
> + av_dict_set(&encoder_opts, "preset", "medium", 0); /* performance/quality high-level configuration */
> + av_dict_set(&encoder_opts, "profile", "baseline", 0); /* H264 specific profile */
> + if ((ret = avcodec_open2(enc_ctx, enc, &encoder_opts)) < 0) {
> + av_log(NULL, AV_LOG_ERROR, "Cannot open video encoder\n");
> + return ret;
> + }
> + av_dump_format(ofmt_ctx, 0, filename, 1);
> +
> + if (!(ofmt_ctx->oformat->flags & AVFMT_NOFILE)) {
> + ret = avio_open(&ofmt_ctx->pb, filename, AVIO_FLAG_WRITE);
> + if (ret < 0) {
> + fprintf(stderr, "Could not open output file '%s'", filename);
> + return ret;
> + }
> + }
> +
> + /* init muxer, write output file header */
> + ret = avformat_write_header(ofmt_ctx, NULL);
> + if (ret < 0) {
> + fprintf(stderr, "Error occurred when opening output file\n");
> + return ret;
> + }
> +
> + return 0;
> +}
> +
> +static int init_filters(const char *filters_descr)
> +{
> + char args[512];
> + int ret = 0;
> + AVFilter *buffersrc = avfilter_get_by_name("buffer");
> + AVFilter *buffersink = avfilter_get_by_name("buffersink");
> + AVFilterInOut *outputs = avfilter_inout_alloc();
> + AVFilterInOut *inputs = avfilter_inout_alloc();
> +
> + filter_graph = avfilter_graph_alloc();
> + if (!outputs || !inputs || !filter_graph) {
> + ret = AVERROR(ENOMEM);
> + goto end;
> + }
> +
> + /* buffer video source: the decoded frames from the decoder will be inserted here. */
> + snprintf(args, sizeof(args),
> + "video_size=%dx%d:pix_fmt=%d:time_base=%d/%d:pixel_aspect=%d/%d",
> + dec_ctx->width, dec_ctx->height, dec_ctx->pix_fmt,
> + dec_ctx->time_base.num, dec_ctx->time_base.den,
> + dec_ctx->sample_aspect_ratio.num, dec_ctx->sample_aspect_ratio.den);
> +
> + ret = avfilter_graph_create_filter(&buffersrc_ctx, buffersrc, "in",
> + args, NULL, filter_graph);
In this case, you serialize the options into a string, and below, for the
output, you use av_opt_set. If you want to illustrate the two possibilities,
please add a comment to explain. And if not, better use options everywhere.
> + if (ret < 0) {
> + av_log(NULL, AV_LOG_ERROR, "Cannot create buffer source\n");
> + goto end;
> + }
> +
> + /* buffer video sink: to terminate the filter chain. */
> + ret = avfilter_graph_create_filter(&buffersink_ctx, buffersink, "out",
> + NULL, NULL, filter_graph);
> + if (ret < 0) {
> + av_log(NULL, AV_LOG_ERROR, "Cannot create buffer sink\n");
> + goto end;
> + }
> +
> + ret = av_opt_set_int_list(buffersink_ctx, "pix_fmts", enc_ctx->codec->pix_fmts,
> + AV_PIX_FMT_NONE, AV_OPT_SEARCH_CHILDREN);
> + if (ret < 0) {
> + av_log(NULL, AV_LOG_ERROR, "Cannot set output pixel format\n");
> + goto end;
> + }
> +
> + /* Endpoints for the filter graph. */
> + outputs->name = av_strdup("in");
Here and at a few other places: unchecked memory allocation.
> + outputs->filter_ctx = buffersrc_ctx;
> + outputs->pad_idx = 0;
> + outputs->next = NULL;
> +
> + inputs->name = av_strdup("out");
> + inputs->filter_ctx = buffersink_ctx;
> + inputs->pad_idx = 0;
> + inputs->next = NULL;
> +
> + if ((ret = avfilter_graph_parse_ptr(filter_graph, filters_descr,
> + &inputs, &outputs, NULL)) < 0)
Indentation?
> + goto end;
> +
> + if ((ret = avfilter_graph_config(filter_graph, NULL)) < 0)
> + goto end;
> +
> +end:
> + avfilter_inout_free(&inputs);
> + avfilter_inout_free(&outputs);
> +
> + return ret;
> +}
> +
> +int main(int argc, char **argv)
> +{
> + int ret;
> + AVPacket packet;
> + AVPacket enc_pkt;
> + AVFrame *frame = NULL;
> + AVFrame *filt_frame = NULL;
> + int got_frame;
> +
> + if (argc != 3) {
> + fprintf(stderr, "Usage: %s <input file> <output file>\n", argv[0]);
> + exit(1);
> + }
> +
> + av_register_all();
> + avfilter_register_all();
> +
> + if ((ret = open_input_file(argv[1])) < 0)
> + goto end;
> + if ((ret = open_output_file(argv[2])) < 0)
> + goto end;
> + if ((ret = init_filters(filter_descr)) < 0)
> + goto end;
> +
> + /* read all packets */
> + while (1) {
> + if ((ret = av_read_frame(ifmt_ctx, &packet)) < 0)
> + break;
> +
> + if (packet.stream_index == video_stream_index) {
> + got_frame = 0;
I believe it is unneeded.
> + frame = av_frame_alloc();
Unchecked memory allocation.
> + ret = avcodec_decode_video2(dec_ctx, frame, &got_frame, &packet);
> + if (ret < 0) {
> + av_frame_free(&frame);
> + av_log(NULL, AV_LOG_ERROR, "Error decoding video\n");
> + break;
> + }
> +
> + if (got_frame) {
> + frame->pts = av_frame_get_best_effort_timestamp(frame);
> +
> + /* push the decoded frame into the filtergraph */
> + ret = av_buffersrc_add_frame_flags(buffersrc_ctx, frame, AV_BUFFERSRC_FLAG_KEEP_REF);
> + av_frame_free(&frame);
Any reason to set the KEEP_REF flag only to free the frame immediately
afterwards?
> + if (ret < 0) {
> + av_log(NULL, AV_LOG_ERROR, "Error while feeding the filtergraph\n");
> + break;
> + }
> +
> + /* pull filtered frames from the filtergraph */
> + while (1) {
> + filt_frame = av_frame_alloc();
> + ret = av_buffersink_get_frame(buffersink_ctx, filt_frame);
> + if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF) {
> + av_frame_free(&filt_frame);
> + break;
> + }
> + if (ret < 0)
> + goto end;
> +
> + enc_pkt.data = NULL;
> + av_init_packet(&enc_pkt);
> + /* encode filtered frame */
> + ret = avcodec_encode_video2(enc_ctx, &enc_pkt, filt_frame, &got_frame);
> + av_frame_free(&filt_frame);
> + if (ret < 0)
> + goto end;
> + if (!got_frame)
> + continue;
> +
> + /* prepare packet for muxing */
> + enc_pkt.stream_index = 0; /* we have only one stream in output */
> +
> + /* mux encoded frame */
> + ret = av_interleaved_write_frame(ofmt_ctx, &enc_pkt);
> + if (ret < 0)
> + goto end;
> + }
> + }
> + av_frame_free(&frame);
> + } else {
> + /* Other elementary streams are discarded in this example.
> + * They may be otherwise also reencoded, or remuxed.
> + */
> + ;
> + }
> + av_free_packet(&packet);
> + }
> + av_write_trailer(ofmt_ctx);
You need to flush the filters and encoder.
To flush the filters, you call av_buffersrc_add_frame_flags() with frame =
NULL, and then you pull frames from the buffersink until it returns EOF.
To flush the encoder, you test for CODEC_CAP_DELAY and call
avcodec_encode_video2() with frame = NULL until it stops returning packets.
> +end:
> + avfilter_graph_free(&filter_graph);
> + avcodec_close(dec_ctx);
> + avcodec_close(enc_ctx);
> + avformat_close_input(&ifmt_ctx);
> + if (ofmt_ctx && !(ofmt_ctx->oformat->flags & AVFMT_NOFILE))
> + avio_close(ofmt_ctx->pb);
> + avformat_free_context(ofmt_ctx);
> + av_frame_free(&frame);
> + av_frame_free(&filt_frame);
> +
> + if (ret < 0 && ret != AVERROR_EOF) {
> + fprintf(stderr, "Error occurred: %s\n", av_err2str(ret));
> + exit(1);
> + }
> +
> + exit(0);
> +}
> --
> 1.8.1.5
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 819 bytes
Desc: Digital signature
URL: <http://ffmpeg.org/pipermail/ffmpeg-devel/attachments/20140130/e9dda489/attachment.asc>
More information about the ffmpeg-devel
mailing list