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Rennes Emotion Map 2010-11
19 octobre 2011, par
Mis à jour : Juillet 2013
Langue : français
Type : Texte
Autres articles (105)
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Black screen when playing a video with ffmpeg and SDL on iOS
1er avril 2012, par patrickI'm attempting to create a video player on iOS using ffmpeg and SDL. I'm decoding the video stream and attempting to convert the pixel data into a SDL_Surface and then convert that over to an SDL_Texture and render it on screen. However, all I'm getting is a black screen. I know the video file is good and can be viewed fine from VLC. Any idea what I'm missing here ?
Initialization code :
// initialize SDL (Simple DirectMedia Layer) to playback the content
if( SDL_Init(SDL_INIT_VIDEO | SDL_INIT_AUDIO | SDL_INIT_TIMER) )
{
DDLogError(@"Unable to initialize SDL");
return NO;
}
// create window and renderer
window = SDL_CreateWindow(NULL, 0, 0, SCREEN_WIDTH, SCREEN_HEIGHT,
SDL_WINDOW_OPENGL | SDL_WINDOW_BORDERLESS |
SDL_WINDOW_SHOWN);
if ( window == 0 )
{
DDLogError(@"Unable to initialize SDL Window");
}
renderer = SDL_CreateRenderer(window, -1, 0);
if ( !renderer )
{
DDLogError(@"Unable to initialize SDL Renderer");
}
// Initialize the FFMpeg and register codecs and their respected file formats
av_register_all();Playback code :
AVFormatContext *formatContext = NULL ;DDLogInfo(@"Opening media file at location:%@", filePath);
const char *filename = [filePath cStringUsingEncoding:NSUTF8StringEncoding];
// Open media file
if( avformat_open_input(&formatContext, filename, NULL, NULL) != 0 )
{
DDLogWarn(@"Unable to open media file. [File:%@]", filePath);
NSString *failureReason = NSLocalizedString(@"Unable to open file.", @"Media playback failed, unable to open file.");
if ( error != NULL )
{
*error = [NSError errorWithDomain:MediaPlayerErrorDomain
code:UNABLE_TO_OPEN
userInfo:[NSDictionary dictionaryWithObject:failureReason
forKey:NSLocalizedFailureReasonErrorKey]];
}
return NO; // Couldn't open file
}
// Retrieve stream information
if( avformat_find_stream_info(formatContext, NULL) <= 0 )
{
DDLogWarn(@"Unable to locate stream information for file. [File:%@]", filePath);
NSString *failureReason = NSLocalizedString(@"Unable to find audio/video stream information.", @"Media playback failed, unable to find stream information.");
if ( error != NULL )
{
*error = [NSError errorWithDomain:MediaPlayerErrorDomain
code:UNABLE_TO_FIND_STREAM
userInfo:[NSDictionary dictionaryWithObject:failureReason
forKey:NSLocalizedFailureReasonErrorKey]];
}
return NO; // Missing stream information
}
// Find the first video or audio stream
int videoStream = -1;
int audioStream = -1;
DDLogInfo(@"Locating stream information for media file");
for( int index=0; index<(formatContext->nb_streams); index++)
{
if( formatContext->streams[index]->codec->codec_type==AVMEDIA_TYPE_VIDEO )
{
DDLogInfo(@"Found video stream");
videoStream = index;
break;
}
else if( mediaType == AUDIO_FILE &&
(formatContext->streams[index]->codec->codec_type==AVMEDIA_TYPE_AUDIO) )
{
DDLogInfo(@"Found audio stream");
audioStream = index;
break;
}
}
if( videoStream == -1 && (audioStream == -1) )
{
DDLogWarn(@"Unable to find video or audio stream for file");
NSString *failureReason = NSLocalizedString(@"Unable to locate audio/video stream.", @"Media playback failed, unable to locate media stream.");
if ( error != NULL )
{
*error = [NSError errorWithDomain:MediaPlayerErrorDomain
code:UNABLE_TO_FIND_STREAM
userInfo:[NSDictionary dictionaryWithObject:failureReason
forKey:NSLocalizedFailureReasonErrorKey]];
}
return NO; // Didn't find a video or audio stream
}
// Get a pointer to the codec context for the video/audio stream
AVCodecContext *codecContext;
DDLogInfo(@"Attempting to locate the codec for the media file");
if ( videoStream > -1 )
{
codecContext = formatContext->streams[videoStream]->codec;
}
else
{
codecContext = formatContext->streams[audioStream]->codec;
}
// Now that we have information about the codec that the file is using,
// we need to actually open the codec to decode the content
DDLogInfo(@"Attempting to open the codec to playback the media file");
AVCodec *codec;
// Find the decoder for the video stream
codec = avcodec_find_decoder(codecContext->codec_id);
if( codec == NULL )
{
DDLogWarn(@"Unsupported codec! Cannot playback meda file [File:%@]", filePath);
NSString *failureReason = NSLocalizedString(@"Unsupported file format. Cannot playback media.", @"Media playback failed, unsupported codec.");
if ( error != NULL )
{
*error = [NSError errorWithDomain:MediaPlayerErrorDomain
code:UNSUPPORTED_CODEC
userInfo:[NSDictionary dictionaryWithObject:failureReason
forKey:NSLocalizedFailureReasonErrorKey]];
}
return NO; // Codec not found
}
// Open codec
if( avcodec_open2(codecContext, codec, NULL) < 0 )
{
DDLogWarn(@"Unable to open codec! Cannot playback meda file [File:%@]", filePath);
NSString *failureReason = NSLocalizedString(@"Unable to open media codec. Cannot playback media.", @"Media playback failed, cannot open codec.");
if ( error != NULL )
{
*error = [NSError errorWithDomain:MediaPlayerErrorDomain
code:UNABLE_TO_LOAD_CODEC
userInfo:[NSDictionary dictionaryWithObject:failureReason
forKey:NSLocalizedFailureReasonErrorKey]];
}
return NO; // Could not open codec
}
// Allocate player frame
AVFrame *playerFrame=avcodec_alloc_frame();
// Allocate an AVFrame structure
AVFrame *RGBframe=avcodec_alloc_frame();
if( RGBframe==NULL )
{
// could not create a frame to convert our video frame
// to a 16-bit RGB565 frame.
DDLogWarn(@"Unable to convert video frame. Cannot playback meda file [File:%@]", filePath);
NSString *failureReason = NSLocalizedString(@"Problems interpreting video frame information.", @"Media playback failed, cannot convert frame.");
if ( error != NULL )
{
*error = [NSError errorWithDomain:MediaPlayerErrorDomain
code:UNABLE_TO_LOAD_FRAME
userInfo:[NSDictionary dictionaryWithObject:failureReason
forKey:NSLocalizedFailureReasonErrorKey]];
}
return NO; // Could not open codec
}
int frameFinished = 0;
AVPacket packet;
// Figure out the destination width/height based on the screen size
int destHeight = codecContext->height;
int destWidth = codecContext->width;
if ( destHeight > SCREEN_HEIGHT || (destWidth > SCREEN_WIDTH) )
{
if ( destWidth > SCREEN_WIDTH )
{
float percentDiff = ( destWidth - SCREEN_WIDTH ) / (float)destWidth;
destWidth = destWidth - (int)(destWidth * percentDiff );
destHeight = destHeight - (int)(destHeight * percentDiff );
}
if ( destHeight > SCREEN_HEIGHT )
{
float percentDiff = (destHeight - SCREEN_HEIGHT ) / (float)destHeight;
destWidth = destWidth - (int)(destWidth * percentDiff );
destHeight = destHeight - (int)(destHeight * percentDiff );
}
}
SwsContext *swsContext = sws_getContext(codecContext->width, codecContext->height, codecContext->pix_fmt, destWidth, destHeight, PIX_FMT_RGB565, SWS_BICUBIC, NULL, NULL, NULL);
while( av_read_frame(formatContext, &packet) >= 0 )
{
// Is this a packet from the video stream?
if( packet.stream_index == videoStream )
{
// Decode video frame
avcodec_decode_video2(codecContext, playerFrame, &frameFinished, &packet);
// Did we get a video frame?
if( frameFinished != 0 )
{
// Convert the content over to RGB565 (16-bit RGB) to playback with SDL
uint8_t *dst[3];
int dstStride[3];
// Set the destination stride
for (int plane = 0; plane < 3; plane++)
{
dstStride[plane] = codecContext->width*2;
dst[plane]= (uint8_t*) malloc(dstStride[plane]*destHeight);
}
sws_scale(swsContext, playerFrame->data,
playerFrame->linesize, 0,
destHeight,
dst, dstStride);
// Create the SDL surface frame that we are going to use to draw our video
// 16-bit RGB so 2 bytes per pixel (pitch = width*(bytes per pixel))
int pitch = destWidth*2;
SDL_Surface *frameSurface = SDL_CreateRGBSurfaceFrom(dst[0], destWidth, destHeight, 16, pitch, 0, 0, 0, 0);
// Clear the old frame first
SDL_RenderClear(renderer);
// Move the frame over to a texture and render it on screen
SDL_Texture *texture = SDL_CreateTextureFromSurface(renderer, frameSurface);
SDL_SetTextureBlendMode(texture, SDL_BLENDMODE_BLEND);
// Draw the new frame on the screen
SDL_RenderPresent(renderer);
SDL_DestroyTexture(texture);
SDL_FreeSurface(frameSurface);
} -
ffmpeg : affect source stream index in new_output_stream function
29 mars 2012, par Matthieu Bouronffmpeg : affect source stream index in new_output_stream function
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mpegts : fix a unused function warning
2 avril 2012, par Michael Niedermayermpegts : fix a unused function warning
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