[FFmpeg-devel,v1,4/4] examples: seperate vaapi_decode from hw_decode

diff --git a/configure b/configure
index 196873c4aa..73ed62eae7 100755
--- a/configure
+++ b/configure
@@ -1744,6 +1744,7 @@  EXAMPLE_LIST="
     scaling_video_example
     transcode_aac_example
     transcoding_example
+    vaapi_decode_example
     vaapi_encode_example
     vaapi_transcode_example
 "
@@ -3779,6 +3780,7 @@  resampling_audio_example_deps="avutil swresample"
 scaling_video_example_deps="avutil swscale"
 transcode_aac_example_deps="avcodec avformat swresample"
 transcoding_example_deps="avfilter avcodec avformat avutil"
+vaapi_decode_example_deps="avcodec avformat avutil"
 vaapi_encode_example_deps="avcodec avutil h264_vaapi_encoder"
 vaapi_transcode_example_deps="avcodec avformat avutil h264_vaapi_encoder"
 
diff --git a/doc/examples/Makefile b/doc/examples/Makefile
index 81bfd34d5d..f1b18028c5 100644
--- a/doc/examples/Makefile
+++ b/doc/examples/Makefile
@@ -19,6 +19,7 @@  EXAMPLES-$(CONFIG_RESAMPLING_AUDIO_EXAMPLE)  += resampling_audio
 EXAMPLES-$(CONFIG_SCALING_VIDEO_EXAMPLE)     += scaling_video
 EXAMPLES-$(CONFIG_TRANSCODE_AAC_EXAMPLE)     += transcode_aac
 EXAMPLES-$(CONFIG_TRANSCODING_EXAMPLE)       += transcoding
+EXAMPLES-$(CONFIG_VAAPI_DECODE_EXAMPLE)      += vaapi_decode
 EXAMPLES-$(CONFIG_VAAPI_ENCODE_EXAMPLE)      += vaapi_encode
 EXAMPLES-$(CONFIG_VAAPI_TRANSCODE_EXAMPLE)   += vaapi_transcode
 
diff --git a/doc/examples/vaapi_decode.c b/doc/examples/vaapi_decode.c
new file mode 100644
index 0000000000..a9c8d48240
--- /dev/null
+++ b/doc/examples/vaapi_decode.c
@@ -0,0 +1,296 @@ 
+/*
+ * Video Acceleration API (video decoding) decode sample
+ *
+ * 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
+ * VAAPI-accelerated decoding example.
+ *
+ * @example vaapi_decode.c
+ * This example shows how to do VAAPI-accelerated decoding with output
+ * frames from the HW video surfaces. Also support decoding with sub frame.
+ */
+
+#include <stdio.h>
+
+#include <libavcodec/avcodec.h>
+#include <libavformat/avformat.h>
+#include <libavutil/pixdesc.h>
+#include <libavutil/hwcontext.h>
+#include <libavutil/opt.h>
+#include <libavutil/avassert.h>
+#include <libavutil/imgutils.h>
+
+static AVBufferRef *hw_device_ctx = NULL;
+static enum AVPixelFormat hw_pix_fmt;
+static FILE *output_file = NULL;
+static FILE *sub_frame_output = NULL;
+
+static int hw_decoder_init(AVCodecContext *ctx, const enum AVHWDeviceType type)
+{
+    int err = 0;
+
+    if ((err = av_hwdevice_ctx_create(&hw_device_ctx, type,
+                                      NULL, NULL, 0)) < 0) {
+        fprintf(stderr, "Failed to create specified HW device.\n");
+        return err;
+    }
+    ctx->hw_device_ctx = av_buffer_ref(hw_device_ctx);
+
+    return err;
+}
+
+static enum AVPixelFormat get_hw_format(AVCodecContext *ctx,
+                                        const enum AVPixelFormat *pix_fmts)
+{
+    const enum AVPixelFormat *p;
+
+    for (p = pix_fmts; *p != -1; p++) {
+        if (*p == hw_pix_fmt)
+            return *p;
+    }
+
+    fprintf(stderr, "Failed to get HW surface format.\n");
+    return AV_PIX_FMT_NONE;
+}
+
+static int retrieve_write(AVFrame *frame, AVFrame *sw_frame, FILE *file)
+{
+    AVFrame *tmp_frame = NULL;
+    uint8_t *buffer = NULL;
+    int size;
+    int ret = 0;
+
+    if (frame->format == hw_pix_fmt) {
+        /* retrieve data from GPU to CPU */
+        if ((ret = av_hwframe_transfer_data(sw_frame, frame, 0)) < 0) {
+            fprintf(stderr, "Error transferring the data to system memory\n");
+            goto fail;
+        }
+        tmp_frame = sw_frame;
+    } else
+        tmp_frame = frame;
+
+    size = av_image_get_buffer_size(tmp_frame->format, tmp_frame->width,
+                                    tmp_frame->height, 1);
+    buffer = av_malloc(size);
+    if (!buffer) {
+        fprintf(stderr, "Can not alloc buffer\n");
+        ret = AVERROR(ENOMEM);
+        goto fail;
+    }
+    ret = av_image_copy_to_buffer(buffer, size,
+                                  (const uint8_t * const *)tmp_frame->data,
+                                  (const int *)tmp_frame->linesize, tmp_frame->format,
+                                  tmp_frame->width, tmp_frame->height, 1);
+    if (ret < 0) {
+        fprintf(stderr, "Can not copy image to buffer\n");
+        goto fail;
+    }
+
+    if ((ret = fwrite(buffer, 1, size, file)) < 0) {
+        fprintf(stderr, "Failed to dump raw data.\n");
+        goto fail;
+    }
+
+fail:
+    av_freep(&buffer);
+
+    return ret;
+}
+
+static int decode_write(AVCodecContext *avctx, AVPacket *packet)
+{
+    AVFrame *frame = NULL, *sw_frame = NULL;
+    AVFrame *sub_frame = NULL, *sw_sub_frame = NULL;
+    AVFrameSideData *sd = NULL;
+    int ret = 0;
+
+    ret = avcodec_send_packet(avctx, packet);
+    if (ret < 0) {
+        fprintf(stderr, "Error during decoding\n");
+        return ret;
+    }
+
+    while (1) {
+        if (!(frame = av_frame_alloc()) || !(sw_frame = av_frame_alloc())) {
+            fprintf(stderr, "Can not alloc frame\n");
+            ret = AVERROR(ENOMEM);
+            goto fail;
+        }
+
+        ret = avcodec_receive_frame(avctx, frame);
+        if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF) {
+            av_frame_free(&frame);
+            av_frame_free(&sw_frame);
+            return 0;
+        } else if (ret < 0) {
+            fprintf(stderr, "Error while decoding\n");
+            goto fail;
+        }
+
+        ret = retrieve_write(frame, sw_frame, output_file);
+        if (ret < 0) {
+            fprintf(stderr, "Error while retrieve and write data\n");
+            goto fail;
+        }
+
+        sd = av_frame_get_side_data(frame, AV_FRAME_DATA_SUB_FRAME);
+        if (sd) {
+            if (!(sw_sub_frame = av_frame_alloc())) {
+                fprintf(stderr, "Can not alloc sub frame\n");
+                ret = AVERROR(ENOMEM);
+                goto fail;
+            }
+
+            sub_frame = (AVFrame *)sd->data;
+
+            ret = retrieve_write(sub_frame, sw_sub_frame, sub_frame_output);
+            if (ret < 0) {
+                fprintf(stderr, "Error while retrieve and write sub frame data\n");
+                goto fail;
+            }
+
+            av_frame_remove_side_data(frame, AV_FRAME_DATA_SUB_FRAME);
+            sd = NULL;
+        }
+
+    fail:
+        av_frame_free(&frame);
+        av_frame_free(&sw_frame);
+        av_frame_free(&sw_sub_frame);
+        if (ret < 0)
+            return ret;
+    }
+}
+
+int main(int argc, char *argv[])
+{
+    AVFormatContext *input_ctx = NULL;
+    AVStream *video = NULL;
+    AVCodecContext *decoder_ctx = NULL;
+    const AVCodec *decoder = NULL;
+    AVPacket *packet = NULL;
+    int video_stream, ret, i;
+
+    if (argc !=3 && argc != 5) {
+        fprintf(stderr, "Decode only Usage: %s <input file> <output file>\n", argv[0]);
+        fprintf(stderr, "Decode with sub frame Usage: %s <input file> <output file> <sfc_width:sfc_height:sfc_format> <sub frame output file>\n", argv[0]);
+        return -1;
+    }
+
+    // av_log_set_level(AV_LOG_DEBUG);
+
+    packet = av_packet_alloc();
+    if (!packet) {
+        fprintf(stderr, "Failed to allocate AVPacket\n");
+        return -1;
+    }
+
+    /* open the input file */
+    if (avformat_open_input(&input_ctx, argv[1], NULL, NULL) != 0) {
+        fprintf(stderr, "Cannot open input file '%s'\n", argv[1]);
+        return -1;
+    }
+
+    if (avformat_find_stream_info(input_ctx, NULL) < 0) {
+        fprintf(stderr, "Cannot find input stream information.\n");
+        return -1;
+    }
+
+    /* find the video stream information */
+    ret = av_find_best_stream(input_ctx, AVMEDIA_TYPE_VIDEO, -1, -1, &decoder, 0);
+    if (ret < 0) {
+        fprintf(stderr, "Cannot find a video stream in the input file\n");
+        return -1;
+    }
+    video_stream = ret;
+
+    for (i = 0;; i++) {
+        const AVCodecHWConfig *config = avcodec_get_hw_config(decoder, i);
+        if (!config) {
+            fprintf(stderr, "Decoder %s does not support device type %s.\n",
+                    decoder->name, av_hwdevice_get_type_name(AV_HWDEVICE_TYPE_VAAPI));
+            return -1;
+        }
+        if (config->methods & AV_CODEC_HW_CONFIG_METHOD_HW_DEVICE_CTX &&
+            config->device_type == AV_HWDEVICE_TYPE_VAAPI) {
+            hw_pix_fmt = config->pix_fmt;
+            break;
+        }
+    }
+
+    if (!(decoder_ctx = avcodec_alloc_context3(decoder)))
+        return AVERROR(ENOMEM);
+
+    video = input_ctx->streams[video_stream];
+    if (avcodec_parameters_to_context(decoder_ctx, video->codecpar) < 0)
+        return -1;
+
+    decoder_ctx->get_format  = get_hw_format;
+
+    if (argc == 5) {
+        sub_frame_output = fopen(argv[4], "w+b");
+        decoder_ctx->export_side_data =  decoder_ctx->export_side_data | AV_CODEC_EXPORT_DATA_SUB_FRAME;
+        if ((ret = av_dict_parse_string(&decoder_ctx->sub_frame_opts, argv[3], "=", ":", 0)) < 0) {
+            av_log(decoder_ctx, AV_LOG_ERROR, "Failed to parse option string '%s'.\n", argv[3]);
+            av_dict_free(&decoder_ctx->sub_frame_opts);
+            return -1;
+        }
+    }
+
+    if (hw_decoder_init(decoder_ctx, AV_HWDEVICE_TYPE_VAAPI) < 0)
+        return -1;
+
+    if ((ret = avcodec_open2(decoder_ctx, decoder, NULL)) < 0) {
+        fprintf(stderr, "Failed to open codec for stream #%u\n", video_stream);
+        return -1;
+    }
+
+    /* open the file to dump raw data */
+    output_file = fopen(argv[2], "w+b");
+
+    /* actual decoding and dump the raw data */
+    while (ret >= 0) {
+        if ((ret = av_read_frame(input_ctx, packet)) < 0)
+            break;
+
+        if (video_stream == packet->stream_index)
+            ret = decode_write(decoder_ctx, packet);
+
+        av_packet_unref(packet);
+    }
+
+    /* flush the decoder */
+    ret = decode_write(decoder_ctx, NULL);
+
+    if (output_file)
+        fclose(output_file);
+    if (sub_frame_output)
+        fclose(sub_frame_output);
+    av_packet_free(&packet);
+    av_dict_free(&decoder_ctx->sub_frame_opts);
+    avcodec_free_context(&decoder_ctx);
+    avformat_close_input(&input_ctx);
+    av_buffer_unref(&hw_device_ctx);
+
+    return 0;
+}