[FFmpeg-cvslog] doc/examples: add decoding/filtering example program
Stefano Sabatini
git at videolan.org
Sun Jul 10 18:09:19 CEST 2011
ffmpeg | branch: master | Stefano Sabatini <stefano.sabatini-lala at poste.it> | Tue Jun 21 00:33:37 2011 +0200| [fcc7d869d98838356e3e778afe2196a12bfcd2b1] | committer: Stefano Sabatini
doc/examples: add decoding/filtering example program
> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=fcc7d869d98838356e3e778afe2196a12bfcd2b1
---
doc/examples/Makefile | 2 +-
doc/examples/filtering.c | 230 ++++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 231 insertions(+), 1 deletions(-)
diff --git a/doc/examples/Makefile b/doc/examples/Makefile
index f8abdff..fde2256 100644
--- a/doc/examples/Makefile
+++ b/doc/examples/Makefile
@@ -3,7 +3,7 @@ FFMPEG_LIBS=libavdevice libavformat libavfilter libavcodec libswscale libavutil
CFLAGS+=$(shell pkg-config --cflags $(FFMPEG_LIBS))
LDFLAGS+=$(shell pkg-config --libs $(FFMPEG_LIBS))
-EXAMPLES=encoding metadata muxing
+EXAMPLES=encoding filtering metadata muxing
OBJS=$(addsuffix .o,$(EXAMPLES))
diff --git a/doc/examples/filtering.c b/doc/examples/filtering.c
new file mode 100644
index 0000000..369cc03
--- /dev/null
+++ b/doc/examples/filtering.c
@@ -0,0 +1,230 @@
+/*
+ * Copyright (c) 2010 Nicolas George
+ * Copyright (c) 2011 Stefano Sabatini
+ *
+ * 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
+ */
+
+#define _XOPEN_SOURCE 600 /* for usleep */
+
+#include <libavcodec/avcodec.h>
+#include <libavformat/avformat.h>
+#include <libavfilter/avfiltergraph.h>
+#include <libavfilter/vsink_buffer.h>
+#include <libavfilter/vsrc_buffer.h>
+
+const char *filter_descr = "scale=78:24";
+
+static AVFormatContext *fmt_ctx;
+static AVCodecContext *dec_ctx;
+AVFilterContext *buffersink_ctx;
+AVFilterContext *buffersrc_ctx;
+AVFilterGraph *filter_graph;
+static int video_stream_index = -1;
+static int64_t last_pts = AV_NOPTS_VALUE;
+
+static int open_input_file(const char *filename)
+{
+ int ret, i;
+ AVCodec *dec;
+
+ 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 = av_find_stream_info(fmt_ctx)) < 0) {
+ av_log(NULL, AV_LOG_ERROR, "Cannot find stream information\n");
+ return ret;
+ }
+
+ /* select the video stream */
+ ret = av_find_best_stream(fmt_ctx, AVMEDIA_TYPE_VIDEO, -1, -1, &dec, 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 = fmt_ctx->streams[video_stream_index]->codec;
+
+ /* init the video decoder */
+ if ((ret = avcodec_open(dec_ctx, dec)) < 0) {
+ av_log(NULL, AV_LOG_ERROR, "Cannot open video decoder\n");
+ return ret;
+ }
+
+ return 0;
+}
+
+static int init_filters(const char *filters_descr)
+{
+ char args[512];
+ int ret;
+ AVFilter *buffersrc = avfilter_get_by_name("buffer");
+ AVFilter *buffersink = avfilter_get_by_name("buffersink");
+ AVFilterInOut *outputs = avfilter_inout_alloc();
+ AVFilterInOut *inputs = avfilter_inout_alloc();
+ enum PixelFormat pix_fmts[] = { PIX_FMT_GRAY8, PIX_FMT_NONE };
+ filter_graph = avfilter_graph_alloc();
+
+ /* buffer video source: the decoded frames from the decoder will be inserted here. */
+ snprintf(args, sizeof(args), "%d:%d:%d:%d:%d:%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");
+ return ret;
+ }
+
+ /* buffer video sink: to terminate the filter chain. */
+ ret = avfilter_graph_create_filter(&buffersink_ctx, buffersink, "out",
+ NULL, pix_fmts, filter_graph);
+ if (ret < 0) {
+ av_log(NULL, AV_LOG_ERROR, "Cannot create buffer sink\n");
+ return ret;
+ }
+
+ /* 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;
+
+ if ((ret = avfilter_graph_parse(filter_graph, filter_descr,
+ &inputs, &outputs, NULL)) < 0)
+ return ret;
+
+ if ((ret = avfilter_graph_config(filter_graph, NULL)) < 0)
+ return ret;
+}
+
+static void display_picref(AVFilterBufferRef *picref, AVRational time_base)
+{
+ int x, y;
+ uint8_t *p0, *p;
+ int64_t delay;
+
+ if (picref->pts != AV_NOPTS_VALUE) {
+ if (last_pts != AV_NOPTS_VALUE) {
+ /* sleep roughly the right amount of time;
+ * usleep is in microseconds, just like AV_TIME_BASE. */
+ delay = av_rescale_q(picref->pts - last_pts,
+ time_base, AV_TIME_BASE_Q);
+ if (delay > 0 && delay < 1000000)
+ usleep(delay);
+ }
+ last_pts = picref->pts;
+ }
+
+ /* Trivial ASCII grayscale display. */
+ p0 = picref->data[0];
+ puts("\033c");
+ for (y = 0; y < picref->video->h; y++) {
+ p = p0;
+ for (x = 0; x < picref->video->w; x++)
+ putchar(" .-+#"[*(p++) / 52]);
+ putchar('\n');
+ p0 += picref->linesize[0];
+ }
+ fflush(stdout);
+}
+
+int main(int argc, char **argv)
+{
+ int ret;
+ AVPacket packet;
+ AVFrame frame;
+ int got_frame;
+
+ if (argc != 2) {
+ fprintf(stderr, "Usage: %s file\n", argv[0]);
+ exit(1);
+ }
+
+ avcodec_register_all();
+ av_register_all();
+ avfilter_register_all();
+
+ if ((ret = open_input_file(argv[1]) < 0))
+ goto end;
+ if ((ret = init_filters(filter_descr)) < 0)
+ goto end;
+
+ /* read all packets */
+ while (1) {
+ AVFilterBufferRef *picref;
+ if ((ret = av_read_frame(fmt_ctx, &packet)) < 0)
+ break;
+
+ if (packet.stream_index == video_stream_index) {
+ avcodec_get_frame_defaults(&frame);
+ got_frame = 0;
+ ret = avcodec_decode_video2(dec_ctx, &frame, &got_frame, &packet);
+ av_free_packet(&packet);
+ if (ret < 0) {
+ av_log(NULL, AV_LOG_ERROR, "Error decoding video\n");
+ break;
+ }
+
+ if (got_frame) {
+ if (frame.pts == AV_NOPTS_VALUE)
+ frame.pts = frame.pkt_dts == AV_NOPTS_VALUE ?
+ frame.pkt_dts : frame.pkt_pts;
+ /* push the decoded frame into the filtergraph */
+ av_vsrc_buffer_add_frame(buffersrc_ctx, &frame);
+
+ /* pull filtered pictures from the filtergraph */
+ while (avfilter_poll_frame(buffersink_ctx->inputs[0])) {
+ av_vsink_buffer_get_video_buffer_ref(buffersink_ctx, &picref, 0);
+ if (picref) {
+ display_picref(picref, buffersink_ctx->inputs[0]->time_base);
+ avfilter_unref_buffer(picref);
+ }
+ }
+ }
+ }
+ }
+end:
+ avfilter_graph_free(&filter_graph);
+ if (dec_ctx)
+ avcodec_close(dec_ctx);
+ av_close_input_file(fmt_ctx);
+
+ if (ret < 0 && ret != AVERROR_EOF) {
+ char buf[1024];
+ av_strerror(ret, buf, sizeof(buf));
+ fprintf(stderr, "Error occurred: %s\n", buf);
+ exit(1);
+ }
+
+ exit(0);
+}
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