From 94170e041107a3831fdd39ebb53f4f50d06edea4 Mon Sep 17 00:00:00 2001
From: Anton Khirnov <anton@khirnov.net>
Date: Wed, 30 Jun 2021 11:44:24 +0200
Subject: tools/venc_data_dump: factor out demux/decode code

It can be shared with other simple demux/decode tools.
---
 tools/decode_simple.c | 157 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 157 insertions(+)
 create mode 100644 tools/decode_simple.c

(limited to 'tools/decode_simple.c')

diff --git a/tools/decode_simple.c b/tools/decode_simple.c
new file mode 100644
index 0000000000..b679fd7ce6
--- /dev/null
+++ b/tools/decode_simple.c
@@ -0,0 +1,157 @@
+/*
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/* shared code for simple demux/decode tools */
+
+#include <stdlib.h>
+#include <string.h>
+
+#include "decode_simple.h"
+
+#include "libavformat/avformat.h"
+
+#include "libavcodec/avcodec.h"
+#include "libavcodec/packet.h"
+
+#include "libavutil/dict.h"
+#include "libavutil/error.h"
+#include "libavutil/frame.h"
+
+static int decode_read(DecodeContext *dc, int flush)
+{
+    const int ret_done = flush ? AVERROR_EOF : AVERROR(EAGAIN);
+    int ret = 0;
+
+    while (ret >= 0 &&
+           (dc->max_frames == 0 || dc->decoder->frame_number < dc->max_frames)) {
+        ret = avcodec_receive_frame(dc->decoder, dc->frame);
+        if (ret < 0) {
+            if (ret == AVERROR_EOF) {
+                int err = dc->process_frame(dc, NULL);
+                if (err < 0)
+                    return err;
+            }
+
+            return (ret == ret_done) ? 0 : ret;
+        }
+
+        ret = dc->process_frame(dc, dc->frame);
+        av_frame_unref(dc->frame);
+        if (ret < 0)
+            return ret;
+
+        if (dc->max_frames && dc->decoder->frame_number == dc->max_frames)
+            return 1;
+    }
+
+    return (dc->max_frames == 0 || dc->decoder->frame_number < dc->max_frames) ? 0 : 1;
+}
+
+int ds_run(DecodeContext *dc)
+{
+    int ret;
+
+    ret = avcodec_open2(dc->decoder, NULL, &dc->decoder_opts);
+    if (ret < 0)
+        return ret;
+
+    while (ret >= 0) {
+        ret = av_read_frame(dc->demuxer, dc->pkt);
+        if (ret < 0)
+            goto flush;
+        if (dc->pkt->stream_index != dc->stream->index) {
+            av_packet_unref(dc->pkt);
+            continue;
+        }
+
+        ret = avcodec_send_packet(dc->decoder, dc->pkt);
+        if (ret < 0) {
+            fprintf(stderr, "Error decoding: %d\n", ret);
+            return ret;
+        }
+        av_packet_unref(dc->pkt);
+
+        ret = decode_read(dc, 0);
+        if (ret < 0) {
+            fprintf(stderr, "Error decoding: %d\n", ret);
+            return ret;
+        } else if (ret > 0)
+            return 0;
+    }
+
+flush:
+    avcodec_send_packet(dc->decoder, NULL);
+    ret = decode_read(dc, 1);
+    if (ret < 0) {
+        fprintf(stderr, "Error flushing: %d\n", ret);
+        return ret;
+    }
+
+    return 0;
+}
+
+void ds_free(DecodeContext *dc)
+{
+    av_dict_free(&dc->decoder_opts);
+
+    av_frame_free(&dc->frame);
+    av_packet_free(&dc->pkt);
+
+    avcodec_free_context(&dc->decoder);
+    avformat_close_input(&dc->demuxer);
+}
+
+int ds_open(DecodeContext *dc, const char *url, int stream_idx)
+{
+    const AVCodec *codec;
+    int ret;
+
+    memset(dc, 0, sizeof(*dc));
+
+    dc->pkt   = av_packet_alloc();
+    dc->frame = av_frame_alloc();
+    if (!dc->pkt || !dc->frame) {
+        ret = AVERROR(ENOMEM);
+        goto fail;
+    }
+
+    ret = avformat_open_input(&dc->demuxer, url, NULL, NULL);
+    if (ret < 0) {
+        fprintf(stderr, "Error opening input file: %d\n", ret);
+        return ret;
+    }
+
+    if (stream_idx < 0 || stream_idx >= dc->demuxer->nb_streams)
+        return AVERROR(EINVAL);
+
+    dc->stream = dc->demuxer->streams[stream_idx];
+
+    codec = avcodec_find_decoder(dc->stream->codecpar->codec_id);
+    if (!codec)
+        return AVERROR_DECODER_NOT_FOUND;
+
+    dc->decoder = avcodec_alloc_context3(codec);
+    if (!dc->decoder)
+        return AVERROR(ENOMEM);
+
+    return 0;
+
+fail:
+    ds_free(dc);
+    return ret;
+}
-- 
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