Merge commit '7b1f03477f1a43d2261fbd83e50a4ad90c7f806d'

* commit '7b1f03477f1a43d2261fbd83e50a4ad90c7f806d':
  examples/avcodec: split the remaining two examples into separate files

Merged-by: Clément Bœsch <u@pkh.me>

1 files changed, 182 insertions, 0 deletions

diff --git a/doc/examples/decode_video.c b/doc/examples/decode_video.c
new file mode 100644
index 0000000000..159765360f
--- /dev/null
+++ b/doc/examples/decode_video.c
@@ -0,0 +1,182 @@
+/*
+ * Copyright (c) 2001 Fabrice Bellard
+ *
+ * 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
+ * video decoding with libavcodec API example
+ *
+ * @example decode_video.c
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <libavcodec/avcodec.h>
+
+#define INBUF_SIZE 4096
+
+static void pgm_save(unsigned char *buf, int wrap, int xsize, int ysize,
+                     char *filename)
+{
+    FILE *f;
+    int i;
+
+    f = fopen(filename,"w");
+    fprintf(f, "P5\n%d %d\n%d\n", xsize, ysize, 255);
+    for (i = 0; i < ysize; i++)
+        fwrite(buf + i * wrap, 1, xsize, f);
+    fclose(f);
+}
+
+static int decode_write_frame(const char *outfilename, AVCodecContext *avctx,
+                              AVFrame *frame, int *frame_count, AVPacket *pkt, int last)
+{
+    int len, got_frame;
+    char buf[1024];
+
+    len = avcodec_decode_video2(avctx, frame, &got_frame, pkt);
+    if (len < 0) {
+        fprintf(stderr, "Error while decoding frame %d\n", *frame_count);
+        return len;
+    }
+    if (got_frame) {
+        printf("Saving %sframe %3d\n", last ? "last " : "", *frame_count);
+        fflush(stdout);
+
+        /* the picture is allocated by the decoder, no need to free it */
+        snprintf(buf, sizeof(buf), outfilename, *frame_count);
+        pgm_save(frame->data[0], frame->linesize[0],
+                 frame->width, frame->height, buf);
+        (*frame_count)++;
+    }
+    if (pkt->data) {
+        pkt->size -= len;
+        pkt->data += len;
+    }
+    return 0;
+}
+
+int main(int argc, char **argv)
+{
+    const char *filename, *outfilename;
+    AVCodec *codec;
+    AVCodecContext *c= NULL;
+    int frame_count;
+    FILE *f;
+    AVFrame *frame;
+    uint8_t inbuf[INBUF_SIZE + AV_INPUT_BUFFER_PADDING_SIZE];
+    AVPacket avpkt;
+
+    if (argc <= 2) {
+        fprintf(stderr, "Usage: %s <input file> <output file>\n", argv[0]);
+        exit(0);
+    }
+    filename    = argv[1];
+    outfilename = argv[2];
+
+    avcodec_register_all();
+
+    av_init_packet(&avpkt);
+
+    /* set end of buffer to 0 (this ensures that no overreading happens for damaged MPEG streams) */
+    memset(inbuf + INBUF_SIZE, 0, AV_INPUT_BUFFER_PADDING_SIZE);
+
+    /* find the MPEG-1 video decoder */
+    codec = avcodec_find_decoder(AV_CODEC_ID_MPEG1VIDEO);
+    if (!codec) {
+        fprintf(stderr, "Codec not found\n");
+        exit(1);
+    }
+
+    c = avcodec_alloc_context3(codec);
+    if (!c) {
+        fprintf(stderr, "Could not allocate video codec context\n");
+        exit(1);
+    }
+
+    if (codec->capabilities & AV_CODEC_CAP_TRUNCATED)
+        c->flags |= AV_CODEC_FLAG_TRUNCATED; // we do not send complete frames
+
+    /* For some codecs, such as msmpeg4 and mpeg4, width and height
+       MUST be initialized there because this information is not
+       available in the bitstream. */
+
+    /* open it */
+    if (avcodec_open2(c, codec, NULL) < 0) {
+        fprintf(stderr, "Could not open codec\n");
+        exit(1);
+    }
+
+    f = fopen(filename, "rb");
+    if (!f) {
+        fprintf(stderr, "Could not open %s\n", filename);
+        exit(1);
+    }
+
+    frame = av_frame_alloc();
+    if (!frame) {
+        fprintf(stderr, "Could not allocate video frame\n");
+        exit(1);
+    }
+
+    frame_count = 0;
+    for (;;) {
+        avpkt.size = fread(inbuf, 1, INBUF_SIZE, f);
+        if (avpkt.size == 0)
+            break;
+
+        /* NOTE1: some codecs are stream based (mpegvideo, mpegaudio)
+           and this is the only method to use them because you cannot
+           know the compressed data size before analysing it.
+
+           BUT some other codecs (msmpeg4, mpeg4) are inherently frame
+           based, so you must call them with all the data for one
+           frame exactly. You must also initialize 'width' and
+           'height' before initializing them. */
+
+        /* NOTE2: some codecs allow the raw parameters (frame size,
+           sample rate) to be changed at any frame. We handle this, so
+           you should also take care of it */
+
+        /* here, we use a stream based decoder (mpeg1video), so we
+           feed decoder and see if it could decode a frame */
+        avpkt.data = inbuf;
+        while (avpkt.size > 0)
+            if (decode_write_frame(outfilename, c, frame, &frame_count, &avpkt, 0) < 0)
+                exit(1);
+    }
+
+    /* Some codecs, such as MPEG, transmit the I- and P-frame with a
+       latency of one frame. You must do the following to have a
+       chance to get the last frame of the video. */
+    avpkt.data = NULL;
+    avpkt.size = 0;
+    decode_write_frame(outfilename, c, frame, &frame_count, &avpkt, 1);
+
+    fclose(f);
+
+    avcodec_free_context(&c);
+    av_frame_free(&frame);
+
+    return 0;
+}