[FFmpeg-devel] [PATCH] Add example reencoding_filtered_video.c
Andrey Utkin
andrey.krieger.utkin at gmail.com
Thu Jan 30 18:12:03 CET 2014
In a comment i have made a statement that filtergraph manages pixel/sample
formats conversion automatically. Actually i am not sure on current state of
it, is it really so? Do we have auto-inserted "format" filter ensuring
conversion to format set for buffersink?
---8<---
---
configure | 2 +
doc/Makefile | 1 +
doc/examples/Makefile | 1 +
doc/examples/reencoding_filtered_video.c | 399 +++++++++++++++++++++++++++++++
4 files changed, 403 insertions(+)
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..900b8c3 100644
--- a/doc/examples/Makefile
+++ b/doc/examples/Makefile
@@ -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..9b0f363
--- /dev/null
+++ b/doc/examples/reencoding_filtered_video.c
@@ -0,0 +1,399 @@
+/*
+ * 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 <assert.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;
+
+ ifmt_ctx = NULL;
+ 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);
+
+ 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;
+
+ ofmt_ctx = NULL;
+ avformat_alloc_output_context2(&ofmt_ctx, NULL, NULL, filename);
+ 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 */
+ 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();
+
+ assert(buffersrc && buffersink && outputs && inputs && filter_graph);
+
+ /* 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);
+ 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");
+ 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;
+
+ assert(outputs->name && inputs->name);
+
+ if ((ret = avfilter_graph_parse_ptr(filter_graph, filters_descr,
+ &inputs, &outputs, NULL)) < 0)
+ goto end;
+
+ if ((ret = avfilter_graph_config(filter_graph, NULL)) < 0)
+ goto end;
+
+end:
+ avfilter_inout_free(&inputs);
+ avfilter_inout_free(&outputs);
+
+ return ret;
+}
+
+static int flush_encoder(void) {
+ int ret;
+ int got_frame;
+ AVPacket enc_pkt;
+
+ while (1) {
+ /* feed encoder with NULL frame to flush it */
+ enc_pkt.data = NULL;
+ av_init_packet(&enc_pkt);
+ ret = avcodec_encode_video2(enc_ctx, &enc_pkt, NULL, &got_frame);
+ if (ret == AVERROR_EOF)
+ return 0;
+ if (ret < 0)
+ break;
+ if (!got_frame)
+ break;
+
+ /* 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)
+ break;
+ }
+ return ret;
+}
+
+static int encode_write_frame(AVFrame *filt_frame) {
+ int ret;
+ int got_frame;
+ AVPacket enc_pkt;
+
+ /* encode filtered frame */
+ enc_pkt.data = NULL;
+ av_init_packet(&enc_pkt);
+ ret = avcodec_encode_video2(enc_ctx, &enc_pkt, NULL, &got_frame);
+ av_frame_free(&filt_frame);
+ if (ret < 0)
+ return ret;
+ if (!got_frame)
+ return 0;
+
+ /* 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);
+ return ret;
+}
+
+static int filter_encode_write_frame(AVFrame *frame) {
+ int ret;
+ AVFrame *filt_frame;
+
+ /* push the decoded frame into the filtergraph */
+ ret = av_buffersrc_add_frame_flags(buffersrc_ctx, frame, 0);
+ if (ret < 0) {
+ av_log(NULL, AV_LOG_ERROR, "Error while feeding the filtergraph\n");
+ return ret;
+ }
+
+ /* pull filtered frames from the filtergraph */
+ while (1) {
+ filt_frame = av_frame_alloc();
+ assert(filt_frame);
+ ret = av_buffersink_get_frame(buffersink_ctx, filt_frame);
+ if (ret < 0) {
+ /* if no more frames for output - returns AVERROR(EAGAIN)
+ * if flushed and no more frames for output - returns AVERROR_EOF
+ * rewrite retcode to 0 to show it as normal procedure completion
+ */
+ if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)
+ ret = 0;
+ av_frame_free(&filt_frame);
+ break;
+ }
+
+ ret = encode_write_frame(filt_frame);
+ if (ret < 0)
+ break;
+ }
+
+ return ret;
+}
+
+int main(int argc, char **argv)
+{
+ int ret;
+ AVPacket packet;
+ AVFrame *frame;
+ int got_frame;
+
+ if (argc != 3) {
+ fprintf(stderr, "Usage: %s <input file> <output file>\n", argv[0]);
+ return 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) {
+ frame = av_frame_alloc();
+ assert(frame);
+ 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);
+
+ ret = filter_encode_write_frame(frame);
+ 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);
+ }
+
+ /* flush filters */
+ ret = filter_encode_write_frame(NULL);
+ if (ret < 0) {
+ fprintf(stderr, "Flushing filters failed\n");
+ goto end;
+ }
+
+ /* flush encoder */
+ ret = flush_encoder();
+ if (ret < 0) {
+ fprintf(stderr, "Flushing encoder failed\n");
+ goto end;
+ }
+
+ av_write_trailer(ofmt_ctx);
+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);
+
+ if (ret < 0)
+ fprintf(stderr, "Error occurred: %s\n", av_err2str(ret));
+
+ return ret ? 1 : 0;
+}
--
1.8.1.5
More information about the ffmpeg-devel
mailing list