[FFmpeg-devel] [PATCH V2] examples/vaapi_dec: Add a VA-API hwaccel decoding example
Jun Zhao
mypopydev at gmail.com
Wed Jul 19 03:50:36 EEST 2017
On 2017/7/19 7:30, Mark Thompson wrote:
> On 17/07/17 03:51, Jun Zhao wrote> On 2017/7/11 15:58, wm4 wrote:
>>> On Tue, 11 Jul 2017 12:06:10 +0800
>>> Jun Zhao <mypopydev at gmail.com> wrote:
>>>
>>>> From 0e4d230ae4c98949a962c6bbdad31d216b54bb6a Mon Sep 17 00:00:00 2001
>>>> From: Jun Zhao <jun.zhao at 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 at intel.com>
>>>> Signed-off-by: Jun Zhao <jun.zhao at 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>
>
> This file is deprecated, and contains nothing useful anyway.
>
Will remove.
>>>> +#include <libavformat/avformat.h>
>>>> +#include <libavutil/pixdesc.h>
>>>> +#include <libavutil/hwcontext.h>
>>>> +#include <libavutil/opt.h>
>>>> +#include <libavutil/hwcontext_vaapi.h>
>
> Shouldn't need any of the API-specific hwcontext includes, just the generic one.
>
Same as above.
>>>> +#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) {
>>>
>>> The implementation already uses your dev_name as default, so you should
>>> be able to drop that, and pass NULL to it.
>>>
>>
>> Yes, will remove the dev_name.
>>
>>>> + 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;
>>>
>>> You could use av_hwframe_transfer_get_formats() instead of hardcoding
>>> it. Might be better if the input is 10 bit, not sure. (Just a
>>> suggestion, up to you.)
>> Ok, it's will show the HW surface/ SW pixel format mapping if we
>> use av_hwframe_transfer_get_formats() instead of hardcoding.
>>
>>>
>>>> + 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;
>>>> + }
>>>> + }
>>>
>>> Using av_image_copy_to_buffer() would be more generic, although it'd
>>> require another allocation/copy in memory. (Just a suggestion.)
>>>
>> Will use av_image_copy_to_buffer().
>>
>>>> +
>>>> + return 0;
>>>> +}
>>>> +
>>>> +int decode_write(AVCodecContext *avctx, AVPacket packet, int flush)
>
> I don't think you mean to pass the packet by value here>
Yes, will use pointer in V3 patch.
>>>> +{
>>>> + 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) {
>>>> + 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;
>
> IIRC passing NULL directly to avcodec_send_packet() is preferable to an empty packet to flush?
>
Will change in the V3 patch :)
>>>> +
>>>> + 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;
>>>> + }
>>>> + }
>
> Maybe replace this block with av_find_best_stream()? (Assuming there isn't some reason I'm missing that that doesn't work...)
Good! This function will reduce about 10 lines code in this example.
>
>>>> +
>>>> + 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;
>>>> +}
>>>
>>> Generally looks OK. Can you replace all references to "vaapi" with "hw"
>>> or so? This code will work for other hwaccels too, and the only things
>>> that need to be switched are the AV_HWDEVICE_TYPE and the decoding
>>> AVPixelFormat. The pixel format still needs to be mapped manually, but
>>> we hope to add new API to make this also generic, so in the end you
>>> could choose the hw implementation by passing a name to it or fully
>>> automatically or so.
>>
>> Good suggestion, will re-work for the general HWAccel decode sample.
>
> Agree. Maybe pass the type name as a first argument to make the command line like "argv[0] <vaapi|dxva2|d3d11va> <input file> <output file>"?
>
> (Those three should work at least. Videotoolbox might work as well, VDPAU would need different output formats. Probably don't want more complexity than that, though, because it wants to be a clear example.)
>
> Rest looks good to me.
>
> Thanks,
>
> - Mark
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