I had successfully followed the LazyFoo tutorials to basic shape/image rendering and am getting over 30 FPS on my RPi3. My next stage is to get video file rendering working. I had used the following code example but the video playback FPS is abysmal.
// sdltest.cpp
// Demonstrates how to play video with SDL2
// Source: http://www.programering.com/a/MTN5EzMwATY.html
#include <stdio.h>
using namespace std;
extern "C"
{
// ffmpeg
#include "libavcodec/avcodec.h"
#include "libavformat/avformat.h"
#include "libswscale/swscale.h"
// SDL
#include <SDL2/SDL.h>
#include <SDL2/SDL_thread.h>
};
#pragma comment(lib,"../lib/avutil.lib")
#pragma comment(lib,"../lib/avcodec.lib")
#pragma comment(lib,"../lib/avformat.lib")
#pragma comment(lib,"../lib/swscale.lib")
#pragma comment(lib,"../lib/sdl2.lib")
int main(int argc, char* argv[])
{
if (argc <= 1)
{
fprintf(stderr, "Usage: <program> <video>\n");
return -1;
}
const char* filename = argv[1];
///////////////////////////////////////////////////////////////////////////////
// ffmpeg
// Register all formats and codecs
av_register_all();
// Open video file
AVFormatContext *pFormatCtx = NULL;
if( avformat_open_input(&pFormatCtx, filename, NULL, NULL) != 0 )
{
return -1; // Couldn't open file
}
// Retrieve stream information
if( avformat_find_stream_info(pFormatCtx, NULL) <0 )
{
return -1; // Couldn't find stream information
}
// Dump information about file onto standard error
av_dump_format(pFormatCtx, 0, filename, 0);
// Find the first video stream
int videoStream = -1;
for(int i=0; i <pFormatCtx->nb_streams; i++)
{
if( pFormatCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO )
{
videoStream = i;
break;
}
}
if( videoStream == -1)
{
return -1; // Didn't find a video stream
}
// Get a pointer to the codec context for the video stream
AVCodecContext * pCodecCtx = pFormatCtx->streams[videoStream]->codec;
// Find the decoder for the video stream
AVCodec* pCodec = avcodec_find_decoder(pCodecCtx->codec_id);
if( pCodec == NULL )
{
fprintf(stderr, "Unsupported codec!\n");
return -1; // Codec not found
}
// Open codec
AVDictionary* optionsDict = NULL;
if( avcodec_open2(pCodecCtx, pCodec, &optionsDict) < 0)
{
return -1; // Could not open codec
}
//Source color format
AVPixelFormat src_fix_fmt = pCodecCtx->pix_fmt; //AV_PIX_FMT_YUV420P
//Objective color format
AVPixelFormat dst_fix_fmt = PIX_FMT_BGR24;
// Allocate video frame
AVFrame* pFrame = av_frame_alloc();
AVFrame* pFrameYUV = av_frame_alloc();
if( pFrameYUV == NULL )
{
return -1;
}
struct SwsContext* sws_ctx = sws_getContext(
pCodecCtx->width,
pCodecCtx->height,
pCodecCtx->pix_fmt,
pCodecCtx->width,
pCodecCtx->height,
dst_fix_fmt,
SWS_BILINEAR,
NULL,
NULL,
NULL);
int numBytes = avpicture_get_size(dst_fix_fmt, pCodecCtx->width, pCodecCtx->height);
uint8_t* buffer = (uint8_t *)av_malloc( numBytes*sizeof(uint8_t) );
avpicture_fill((AVPicture *)pFrameYUV, buffer, dst_fix_fmt, pCodecCtx->width, pCodecCtx->height);
// Read frames and save first five frames to disk
SDL_Rect sdlRect;
sdlRect.x = 0;
sdlRect.y = 0;
sdlRect.w = pCodecCtx->width;
sdlRect.h = pCodecCtx->height;
//////////////////////////////////////////////////////
// SDL
if( SDL_Init(SDL_INIT_VIDEO | SDL_INIT_AUDIO | SDL_INIT_TIMER ))
{
fprintf(stderr, "Could not initialize SDL - %s\n", SDL_GetError());
exit(1);
}
SDL_Window* sdlWindow = SDL_CreateWindow("Video Window", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, pCodecCtx->width, pCodecCtx->height, SDL_WINDOW_OPENGL);
if( !sdlWindow )
{
fprintf(stderr, "SDL: could not set video mode - exiting\n");
exit(1);
}
SDL_Renderer* sdlRenderer = SDL_CreateRenderer(sdlWindow, -1, SDL_RENDERER_ACCELERATED | SDL_RENDERER_PRESENTVSYNC | SDL_RENDERER_TARGETTEXTURE);
SDL_Texture* sdlTexture = SDL_CreateTexture(sdlRenderer, SDL_PIXELFORMAT_BGR24, SDL_TEXTUREACCESS_STATIC, pCodecCtx->width, pCodecCtx->height);
if(!sdlTexture)
{
return -1;
}
SDL_SetTextureBlendMode(sdlTexture,SDL_BLENDMODE_BLEND );
AVPacket packet;
SDL_Event event;
while( av_read_frame(pFormatCtx, &packet) >= 0)
{
// Is this a packet from the video stream?
if( packet.stream_index == videoStream)
{
// Decode video frame
int frameFinished;
avcodec_decode_video2(pCodecCtx, pFrame, &frameFinished, &packet);
// Did we get a video frame?
if( frameFinished )
{
sws_scale(sws_ctx, (uint8_t const * const *)pFrame->data, pFrame->linesize, 0, pCodecCtx->height, pFrameYUV->data, pFrameYUV->linesize);
SDL_UpdateTexture( sdlTexture, &sdlRect, pFrameYUV->data[0], pFrameYUV->linesize[0] );
SDL_RenderClear( sdlRenderer );
SDL_RenderCopy( sdlRenderer, sdlTexture, &sdlRect, &sdlRect );
SDL_RenderPresent( sdlRenderer );
}
//SDL_Delay(50);
}
// Free the packet that was allocated by av_read_frame
av_free_packet(&packet);
SDL_PollEvent(&event);
switch( event.type )
{
case SDL_QUIT:
SDL_Quit();
exit(0);
break;
default:
break;
}
}
SDL_DestroyTexture(sdlTexture);
// Free the YUV frame
av_free(pFrame);
av_free(pFrameYUV);
// Close the codec
avcodec_close(pCodecCtx);
// Close the video file
avformat_close_input(&pFormatCtx);
return 0;
}
I have been using all standard raspbian packages and the following Makefile
CFLAGS=-Wall -O3
LDFLAGS=`pkg-config --libs sdl2 SDL2_image SDL2_mixer SDL2_ttf` -lavformat -lavcodec -lswscale -lavutil
sdltest:
g++ $(CFLAGS) -o sdlapp sdltest.cpp $(LDFLAGS)
When run I do get the following message:
[swscaler @ 0x#####] No accelerated colorspace conversion found from yuv420p to bgr24.
Which is why I suspect some aspect is not running with hardware acceleration. There are many video players which claim to use SDL to display and the few that I have tried all seem to perform playback at an acceptable FPS, so I strongly believe I can do it, I just can't seem to figure out the proper magic code.
Any help or suggestions would be greatly appreciated.
