[FFmpeg-devel,V2] examples/vaapi_dec: Add a VA-API hwaccel decoding example

From 0e4d230ae4c98949a962c6bbdad31d216b54bb6a Mon Sep 17 00:00:00 2001
From: Jun Zhao <jun.zhao@intel.com>
Date: Tue, 21 Mar 2017 11:04:41 +0800
Subject: [V2] examples/vaapi_dec: Add a VA-API hwaccel decoding example.

Add a VA-API hwaccel decoding example.

Signed-off-by: Liu, Kaixuan <kaixuan.liu@intel.com>
Signed-off-by: Jun Zhao <jun.zhao@intel.com>
---
 doc/examples/vaapi_dec.c | 266 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 266 insertions(+)
 create mode 100644 doc/examples/vaapi_dec.c

+}

On 2017/7/11 12:38, 刘歧 wrote:
> From 0e4d230ae4c98949a962c6bbdad31d216b54bb6a Mon Sep 17 00:00:00 2001
> From: Jun Zhao <jun.zhao@intel.com>
> Date: Tue, 21 Mar 2017 11:04:41 +0800
> Subject: [V2] examples/vaapi_dec: Add a VA-API hwaccel decoding example.
> 
> Add a VA-API hwaccel decoding example.
> 
> Signed-off-by: Liu, Kaixuan <kaixuan.liu@intel.com>
> Signed-off-by: Jun Zhao <jun.zhao@intel.com>
> ---
>  doc/examples/vaapi_dec.c | 266 +++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 266 insertions(+)
>  create mode 100644 doc/examples/vaapi_dec.c
> 
> diff --git a/doc/examples/vaapi_dec.c b/doc/examples/vaapi_dec.c
> new file mode 100644
> index 0000000000..01320a3b71
> --- /dev/null
> +++ b/doc/examples/vaapi_dec.c
> @@ -0,0 +1,266 @@
> +/*
> + * Video Acceleration API (video decoding) decode sample
> + *
> + * 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
> + */
> +
> +/**
> + * @file
> + * Intel VAAPI-accelerated decoding example.
> + *
> + * @example vaapi_dec.c
> + * This example shows how to do VAAPI-accelerated decoding with output
> + * frames from the VAAPI video surfaces.
> + */
> +
> +#include <stdio.h>
> +#include <libavcodec/avcodec.h>
> +#include <libavcodec/vaapi.h>
> +#include <libavformat/avformat.h>
> +#include <libavutil/pixdesc.h>
> +#include <libavutil/hwcontext.h>
> +#include <libavutil/opt.h>
> +#include <libavutil/hwcontext_vaapi.h>
> +#include <libavutil/avassert.h>
> +
> +static AVBufferRef *hw_device_ctx = NULL;
> +FILE *output_file = NULL;
> +
> +int decoder_init_vaapi(AVCodecContext *ctx)
> +{
> +    int err = 0;
> +    const char *dev_name = "/dev/dri/renderD128";
> +
> +    if ((err = av_hwdevice_ctx_create(&hw_device_ctx, AV_HWDEVICE_TYPE_VAAPI,
> +                                      dev_name, NULL, 0)) < 0) {
> +        fprintf(stderr, "Failed to create a VAAPI device.\n");
> +        return err;
> +    }
> +    ctx->hw_device_ctx = av_buffer_ref(hw_device_ctx);
> +
> +    return err;
> +}
> +
> +static enum AVPixelFormat get_vaapi_format(AVCodecContext *ctx,
> +                                           const enum AVPixelFormat *pix_fmts)
> +{
> +    const enum AVPixelFormat *p;
> +
> +    for (p = pix_fmts; *p != -1; p++) {
> +        if (*p == AV_PIX_FMT_VAAPI)
> +            return *p;
> +    }
> +
> +    return AV_PIX_FMT_NONE;
> +}
> +
> +int retrieve_data(AVFrame *input)
> +{
> +    AVFrame *output = NULL;
> +    int err;
> +    av_assert0(input->format == AV_PIX_FMT_VAAPI);
> +
> +    if (!(output = av_frame_alloc()))
> +        return AVERROR(ENOMEM);
> +    /* default output nv12 */
> +    output->format = AV_PIX_FMT_NV12;
> +    if ((err = av_hwframe_transfer_data(output, input, 0)) < 0) {
> +        fprintf(stderr, "Failed to transfer data to output frame: %d.\n", err);
> +        goto fail;
> +    }
> +
> +    if ((err = av_frame_copy_props(output, input)) < 0) {
> +        av_frame_unref(output);
> +        goto fail;
> +    }
> +
> +    av_frame_unref(input);
> +    av_frame_move_ref(input, output);
> +    av_frame_free(&output);
> +    return 0;
> +
> +fail:
> +    av_frame_free(&output);
> +    return err;
> +}
> +
> +int write_frame(AVFrame *frame)
> +{
> +    int idx, size;
> +    int width = frame->width;
> +    int height = frame->height;
> +
> +    av_assert0(frame && frame->data[0] && output_file);
> +
> +    for (idx = 0; idx < height; idx++) {
> +        if ((size = fwrite(frame->data[0] + idx*frame->linesize[0],
> +                           1, width, output_file)) < 0) {
> +            fprintf(stderr, "Dump Y to file error.\n");
> +            return -1;
> +        }
> +    }
> +
> +    height >>= 1;
> +    for (idx = 0; idx < height; idx++) {
> +        if ((size = fwrite(frame->data[1] + idx*frame->linesize[1],
> +                           1, width, output_file)) < 0) {
> +            fprintf(stderr, "Dump UV to file error.\n");
> +            return -1;
> +        }
> +    }
> +
> +    return 0;
> +}
> +
> +int decode_write(AVCodecContext *avctx, AVPacket packet, int flush)
> +{
> +    AVFrame *frame = NULL;
> +    int ret = 0;
> +
> +    ret = avcodec_send_packet(avctx, &packet);
> +    if (ret < 0 && ret != AVERROR_EOF)
> +        return 0;
> +
> +    if (!(frame = av_frame_alloc()))
> +        return AVERROR(ENOMEM);
> +
> +    ret = avcodec_receive_frame(avctx, frame);
> +    if (ret >= 0) {
> +        /* retrieve data from GPU to CPU */
> +        if ((ret = retrieve_data(frame)) < 0)
> +            goto fail;
> +
> +        if ((ret = write_frame(frame)) < 0)
> +            goto fail;
> +    } else if (flush == 0) {
> What about !flush? or small than 0
I don't like the flush decoder part in this sample, will submit V3 patch to clean the logic for this part.

> +        ret = 0;
> +    }
> +
> +fail:
> +    av_frame_free(&frame);
> +    return ret;
> +}
> +
> +/* flush the decoder */
> +int flush(AVCodecContext *avctx)
> +{
> +    AVPacket packet;
> +    int ret = 0;
> +
> +    av_init_packet(&packet);
> +    packet.data = NULL;
> +    packet.size = 0;
> +
> +    while (1) {
> +        if ((ret = decode_write(avctx, packet, 1)) < 0)
> +            break;
> +    }
> +    av_packet_unref(&packet);
> +
> +    return 0;
> +}
> +
> +int main(int argc, char *argv[])
> +{
> +    AVFormatContext *input_ctx = NULL;
> +    int i, video_stream, ret;
> +    AVCodecContext *decoder_ctx = NULL;
> +    AVCodec *decoder = NULL;
> +    AVPacket packet;
> +
> +    if (argc < 3) {
> +        fprintf(stderr, "Usage: %s <input file> <output file>\n", argv[0]);
> +        return -1;
> +    }
> +
> +    av_register_all();
> +
> +    /* 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, "Couldn't find input stream information.\n");
> +        goto fail;
> +    }
> +
> +    /* find the video stream information */
> +    video_stream = -1;
> +    for (i = 0; i < input_ctx->nb_streams; i++) {
> +        AVStream *st = input_ctx->streams[i];
> +        if (st->codecpar->codec_type == AVMEDIA_TYPE_VIDEO) {
> +            video_stream = i;        /* NOTE: just handle the first video stream */
> +            break;
> +        }
> +    }
> +
> +    if (video_stream == -1) {
> +        fprintf(stderr, "No find a video stream in the input file.\n");
> +        goto fail;
> +    }
> +
> +    /* initialize the video decoder */
> +    if (!(decoder = avcodec_find_decoder(input_ctx->streams[video_stream]->codecpar->codec_id))) {
> +        fprintf(stderr, "Could not find input codec\n");
> +        goto fail;
> +    }
> +
> +    if (!(decoder_ctx = avcodec_alloc_context3(decoder)))
> +        return AVERROR(ENOMEM);
> +
> +    if (avcodec_parameters_to_context(decoder_ctx,
> +                                      input_ctx->streams[video_stream]->codecpar) < 0)
> +        goto fail;
> +
> +    decoder_ctx->get_format  = get_vaapi_format;
> +    av_opt_set_int(decoder_ctx, "refcounted_frames", 1, 0);
> +
> +    if (decoder_init_vaapi(decoder_ctx) < 0)
> +        goto fail;
> +
> +    if ((ret = avcodec_open2(decoder_ctx, decoder, NULL)) < 0) {
> +        fprintf(stderr, "Failed to open codec for stream #%u\n", i);
> +        goto fail;
> +    }
> +
> +    /* open the output file to dump YUV */
> +    output_file = fopen(argv[2], "w+");
> +
> +    /* actual decoding and dump the YUV data */
> +    while (av_read_frame(input_ctx, &packet) >= 0) {
> +        if (video_stream == packet.stream_index)
> +            ret = decode_write(decoder_ctx, packet, 0);
> +        av_packet_unref(&packet);
> +
> +        if (ret < 0)
> +            break;
> +    }
> +
> +    /* flush the decoder */
> +    flush(decoder_ctx);
> +
> +fail:
> +    if (output_file)
> +        fclose(output_file);
> +    avcodec_free_context(&decoder_ctx);
> +    avformat_close_input(&input_ctx);
> +    av_buffer_unref(&hw_device_ctx);
> +
> +    return ret;
> +}
>