Aegisub/aegisub/lavc_keyframes.cpp

// Copyright (c) 2007, 2points
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
//   * Redistributions of source code must retain the above copyright notice,
//     this list of conditions and the following disclaimer.
//   * Redistributions in binary form must reproduce the above copyright notice,
//     this list of conditions and the following disclaimer in the documentation
//     and/or other materials provided with the distribution.
//   * Neither the name of the Aegisub Group nor the names of its contributors
//     may be used to endorse or promote products derived from this software
//     without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
// POSSIBILITY OF SUCH DAMAGE.
//
// -----------------------------------------------------------------------------
//
// AEGISUB
//
// Website: http://aegisub.cellosoft.com
// Contact: mailto:zeratul@cellosoft.com
//


///////////
// Headers
#include "lavc_keyframes.h"

///////////////
// Constructor
LAVCKeyFrames::LAVCKeyFrames(const wxString& filename) 
 : file(0), codecContext(0), codec(0), stream(0), frame(0), 
   streamN(-1) {
	// Open LAVCFile
	file = LAVCFile::Create(filename);

	// Find video stream
	for (unsigned int i = 0; i < file->fctx->nb_streams; ++i) {
		codecContext = file->fctx->streams[i]->codec;
		codecContext->skip_frame = AVDISCARD_NONKEY;
		codecContext->workaround_bugs = FF_BUG_AUTODETECT;
		if (codecContext->codec_type == CODEC_TYPE_VIDEO) {
			stream = file->fctx->streams[i];
			stream->discard = AVDISCARD_NONKEY;
			streamN = i;
			break;
		}
	}
	if (streamN == -1) throw _T("Could not find a video stream");

	// Find codec
	codec = avcodec_find_decoder(codecContext->codec_id);
	if (!codec) throw _T("Could not find suitable video decoder");

	// Open codec
	int result = avcodec_open(codecContext, codec);
	if (result < 0) throw _T("Failed to open video decoder");

	// Allocate frame
	frame = avcodec_alloc_frame();
}

//////////////
// Destructor
LAVCKeyFrames::~LAVCKeyFrames() {
	if (frame) av_free((void*) frame);
	if (codec && codecContext) avcodec_close(codecContext);
	if (file) file->Release();
}

////////////////////////////
// Parse file for keyframes
wxArrayInt LAVCKeyFrames::GetKeyFrames() {
	wxArrayInt keyframes;

	AVPacket packet;
	register unsigned int frameN = 0;		// Number of parsed frames
	while (av_read_frame(file->fctx, &packet) >= 0) {
		// Check if packet is part of video stream
		if (packet.stream_index == streamN) {
			// Increment number of passed frames
			++frameN;
			// Decode frame
			int frameFinished;
			avcodec_decode_video(codecContext, frame, &frameFinished, packet.data, packet.size);

			// Success?
			if(frameFinished) {
				if (frame->key_frame)
					// Aegisub starts counting at frame 0, so the result must be
					// parsed frames - 1
					keyframes.Add(frameN - 1);
				
				// Free packet
				av_free_packet(&packet);
			}
		}
    }

	return keyframes;
}