[FFmpeg-devel] [PATCH] doc/examples: add a simple decoding example.
Clément Bœsch
u at pkh.me
Wed Sep 4 17:55:35 CEST 2013
From: Clément Bœsch <clement at stupeflix.com>
---
.gitignore | 1 +
doc/examples/Makefile | 3 +-
doc/examples/decoding.c | 153 ++++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 156 insertions(+), 1 deletion(-)
create mode 100644 doc/examples/decoding.c
diff --git a/.gitignore b/.gitignore
index 5c90bfb..40ef04c 100644
--- a/.gitignore
+++ b/.gitignore
@@ -35,6 +35,7 @@
/doc/config.texi
/doc/avoptions_codec.texi
/doc/avoptions_format.texi
+/doc/examples/decoding
/doc/examples/decoding_encoding
/doc/examples/demuxing
/doc/examples/filtering_audio
diff --git a/doc/examples/Makefile b/doc/examples/Makefile
index 3d698cc..fbcb1fb 100644
--- a/doc/examples/Makefile
+++ b/doc/examples/Makefile
@@ -11,7 +11,8 @@ CFLAGS += -Wall -g
CFLAGS := $(shell pkg-config --cflags $(FFMPEG_LIBS)) $(CFLAGS)
LDLIBS := $(shell pkg-config --libs $(FFMPEG_LIBS)) $(LDLIBS)
-EXAMPLES= decoding_encoding \
+EXAMPLES= decoding \
+ decoding_encoding \
demuxing \
filtering_video \
filtering_audio \
diff --git a/doc/examples/decoding.c b/doc/examples/decoding.c
new file mode 100644
index 0000000..976b5e8
--- /dev/null
+++ b/doc/examples/decoding.c
@@ -0,0 +1,153 @@
+/*
+ * Copyright (c) 2010 Nicolas George
+ * Copyright (c) 2011 Stefano Sabatini
+ * Copyright (c) 2013 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.
+ */
+
+#include <libavcodec/avcodec.h>
+#include <libavformat/avformat.h>
+
+static AVFormatContext *fmt_ctx;
+static AVCodecContext *dec_ctx;
+static int video_stream_index = -1;
+
+static int open_input_file(const char *filename)
+{
+ int ret;
+ AVCodec *dec;
+ AVDictionary *opts = NULL;
+
+ /* Open the specified input */
+ if ((ret = avformat_open_input(&fmt_ctx, filename, NULL, NULL)) < 0) {
+ av_log(NULL, AV_LOG_ERROR, "Cannot open input file\n");
+ return ret;
+ }
+
+ /* Extract a maximum of stream information from the opened media */
+ if ((ret = avformat_find_stream_info(fmt_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(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, using the new reference counter system */
+ av_dict_set(&opts, "refcounted_frames", "1", 0);
+ if ((ret = avcodec_open2(dec_ctx, dec, &opts)) < 0) {
+ av_log(NULL, AV_LOG_ERROR, "Cannot open video decoder\n");
+ return ret;
+ }
+
+ return 0;
+}
+
+int main(int argc, char **argv)
+{
+ int ret;
+ AVPacket packet;
+ AVFrame *frame = av_frame_alloc();
+ int got_frame;
+
+ if (!frame) {
+ perror("Could not allocate frame");
+ return 1;
+ }
+
+ if (argc != 2) {
+ fprintf(stderr, "Usage: %s file\n", argv[0]);
+ return 1;
+ }
+
+ av_register_all();
+
+ if ((ret = open_input_file(argv[1])) < 0)
+ goto end;
+
+ /* Demux the file */
+ while ((ret = av_read_frame(fmt_ctx, &packet)) >= 0) {
+
+ /* Pick only the packets from the video stream */
+ if (packet.stream_index == video_stream_index) {
+
+ /* Reset the properties of our frame */
+ avcodec_get_frame_defaults(frame);
+
+ /* Attempt to decode the frame from the AVPacket */
+ got_frame = 0;
+ ret = avcodec_decode_video2(dec_ctx, frame, &got_frame, &packet);
+ if (ret < 0) {
+ av_log(NULL, AV_LOG_ERROR, "Error decoding video\n");
+ av_free_packet(&packet);
+ break;
+ }
+
+ /* Make sure it is a complete frame before doing something with it */
+ if (got_frame) {
+
+ /* Grab the estimation of the timestamp of the frame */
+ int64_t pts = av_frame_get_best_effort_timestamp(frame);
+
+ /* Convert it into seconds using the stream time base */
+ double dpts = pts * av_q2d(dec_ctx->time_base);
+
+ /* Do whatever you want with the content, here we display
+ * miscellaneous information about the frame */
+ av_log(NULL, AV_LOG_INFO, "[%.3f] [%c] [%dx%d] [%p %p %p %p] [%d %d %d %d]\n", dpts,
+ av_get_picture_type_char(frame->pict_type), frame->width, frame->height,
+ frame->data[0], frame->data[1], frame->data[2], frame->data[3],
+ frame->linesize[0], frame->linesize[1], frame->linesize[2], frame->linesize[3]);
+ }
+
+ /* We don't need the frame data anymore so we decrement the
+ * reference counter */
+ av_frame_unref(frame);
+ }
+
+ /* Release the data from the packet before re-using it */
+ av_free_packet(&packet);
+ }
+
+end:
+
+ /* Display internal FFmpeg error */
+ if (ret < 0 && ret != AVERROR_EOF) {
+ char buf[1024];
+ av_strerror(ret, buf, sizeof(buf));
+ fprintf(stderr, "Error occurred: %s\n", buf);
+ return 1;
+ }
+
+ /* Cleanup */
+ if (dec_ctx)
+ avcodec_close(dec_ctx);
+ if (fmt_ctx)
+ avformat_close_input(&fmt_ctx);
+ av_frame_free(&frame);
+
+ return 0;
+}
--
1.8.4
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