Aegisub/aegisub/audio_provider_lavc.cpp

// Copyright (c) 2005-2006, Rodrigo Braz Monteiro, Fredrik Mellbin
// 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
// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
// 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
#ifdef WITH_FFMPEG

#ifdef WIN32
#define EMULATE_INTTYPES
#endif
#include <wx/wxprec.h>

/* avcodec.h uses INT64_C in a *single* place. This prolly breaks on Win32,
 * but, well. Let's at least fix it for Linux.
 */
/* Update: this used to be commented out but is now needed on Windows. 
 * Not sure about Linux, so it's wrapped in an ifdef. 
 */
#ifdef WIN32
#define __STDC_CONSTANT_MACROS 1
#include <stdint.h>
#endif /* WIN32 */
/* - done in posix/defines.h
 */


extern "C" {
#include <ffmpeg/avcodec.h>
#include <ffmpeg/avformat.h>
}
#include "mkv_wrap.h"
#include "lavc_file.h"
#include "audio_provider_lavc.h"
#include "lavc_file.h"
#include "utils.h"
#include "options.h"


///////////////
// Constructor
LAVCAudioProvider::LAVCAudioProvider(Aegisub::String _filename)
	: lavcfile(NULL), codecContext(NULL), rsct(NULL), buffer(NULL)
{
	try {
#if 0
	/* since seeking currently is likely to be horribly broken with two
	 * providers accessing the same stream, this is disabled for now.
	 */
	LAVCVideoProvider *vpro_lavc = dynamic_cast<LAVCVideoProvider *>(vpro);
	if (vpro_lavc) {
		lavcfile = vpro->lavcfile->AddRef();
		filename = vpro_lavc->GetFilename();
	} else {
#endif
		lavcfile = LAVCFile::Create(_filename);
		filename = _filename.c_str();
#if 0
	}
#endif
	audStream = -1;
	for (int i = 0; i < (int)lavcfile->fctx->nb_streams; i++) {
		codecContext = lavcfile->fctx->streams[i]->codec;
		if (codecContext->codec_type == CODEC_TYPE_AUDIO) {
			stream = lavcfile->fctx->streams[i];
			audStream = i;
			break;
		}
	}
	if (audStream == -1) {
		codecContext = NULL;
		throw _T("ffmpeg audio provider: Could not find an audio stream");
	}
	AVCodec *codec = avcodec_find_decoder(codecContext->codec_id);
	if (!codec) {
		codecContext = NULL;
		throw _T("ffmpeg audio provider: Could not find a suitable audio decoder");
	}
	if (avcodec_open(codecContext, codec) < 0)
		throw _T("ffmpeg audio provider: Failed to open audio decoder");

	sample_rate = Options.AsInt(_T("Audio Sample Rate"));
	if (!sample_rate)
		sample_rate = codecContext->sample_rate;

	channels = 1;
	/* FIXME: this entire provider always assumes 16-bit audio. Currently that isn't a problem since
	ffmpeg always converts everything to 16-bit, but in the future it might become one. */
	bytes_per_sample = 2; 

	/* aegisub currently supports mono only, so always resample unless it's mono with the desired samplerate */
	if ((sample_rate != codecContext->sample_rate) || (codecContext->channels > 1)) {
		// FIXME: ffmpeg currently doesn't support downmixing audio with more than two channels,
		// remove the following line when it does.
		if (codecContext->channels > 2)
			throw _T("ffmpeg audio provider: Downmixing audio with more than two channels is currently not supported by ffmpeg");
		rsct = audio_resample_init(1, codecContext->channels, sample_rate, codecContext->sample_rate);
		if (!rsct)
			throw _T("ffmpeg audio provider: Failed to initialize resampling");

		resample_ratio = (float)sample_rate / (float)codecContext->sample_rate;
	}
	
	/* libavcodec seems to give back invalid stream length values for Matroska files.
	 * As a workaround, we can use the overall file length.
	 */
	double length;
	if(stream->duration == AV_NOPTS_VALUE)
		length = (double)lavcfile->fctx->duration / AV_TIME_BASE;
	else
		length = (double)stream->duration * av_q2d(stream->time_base);
	num_samples = (int64_t)(length * sample_rate);

	buffer = (int16_t *)malloc(AVCODEC_MAX_AUDIO_FRAME_SIZE);
	if (!buffer)
		throw _T("ffmpeg audio provider: Failed to allocate audio decoding buffer, out of memory?");

	leftover_samples = 0;

	} catch (...) {
		Destroy();
		throw;
	}
}


LAVCAudioProvider::~LAVCAudioProvider()
{
	Destroy();
}

void LAVCAudioProvider::Destroy()
{
	if (buffer)
		free(buffer);
	if (rsct)
		audio_resample_close(rsct);
	if (codecContext)
		avcodec_close(codecContext);
	if (lavcfile)
		lavcfile->Release();
}

void LAVCAudioProvider::GetAudio(void *buf, int64_t start, int64_t count)
{
	int16_t *_buf = (int16_t *)buf;

	int64_t samples_to_decode = num_samples - start; /* samples left to the end of the stream */
	if (count < samples_to_decode) /* haven't reached the end yet, so just decode the requested number of samples */
		samples_to_decode = count;
	if (samples_to_decode < 0) /* requested beyond the end of the stream */
		samples_to_decode = 0;

	/* if we got asked for more samples than there are left in the stream, add zeros to the decoding buffer until
	we have enough to fill the request */
	memset(_buf + samples_to_decode, 0, (count - samples_to_decode) * 2);

	/* do we have leftover samples from last time we were called? */
	if (leftover_samples > 0) {
		/* put them in the output buffer */
		samples_to_decode -= leftover_samples;
		for (std::vector<int16_t>::iterator i = overshoot_buffer.begin(); i != overshoot_buffer.end(); i++) {
			*(_buf++) = *i;
		}
		/* none left */
		leftover_samples = 0;
		overshoot_buffer.clear();
	}

	AVPacket packet;
	while (samples_to_decode > 0 && av_read_frame(lavcfile->fctx, &packet) >= 0) {
		/* we're not dealing with video packets in this here provider */
		if (packet.stream_index == audStream) {
			int size = packet.size;

			while (size > 0) {
				int temp_output_buffer_size = AVCODEC_MAX_AUDIO_FRAME_SIZE; /* see constructor, it malloc()'s buffer to this */
				int retval, decoded_bytes, decoded_samples;
			
				retval = avcodec_decode_audio2(codecContext, buffer, &temp_output_buffer_size, packet.data, size);
				if (retval <= 0)
					throw _T("ffmpeg audio provider: failed to decode audio");
				/* decoding succeeded but the output buffer is empty, go to next packet */
				if (temp_output_buffer_size == 0) {
					av_free_packet(&packet);
					continue;
				}

				decoded_bytes	= temp_output_buffer_size;
				decoded_samples = decoded_bytes / 2; /* 2 bytes per sample */
				size -= decoded_bytes;

				/* do we need to resample? */
				if (rsct) {
					/* allocate some memory to save the resampled data in */
					int16_t *temp_output_buffer = (int16_t *)malloc(AVCODEC_MAX_AUDIO_FRAME_SIZE);
					if (!temp_output_buffer)
						throw _T("ffmpeg audio provider: Failed to allocate audio resampling buffer, out of memory?");

					/* do the actual resampling */
					decoded_samples = audio_resample(rsct, temp_output_buffer, buffer, decoded_samples / codecContext->channels);

					/* did we end up with more samples than we were asked for? */
					if (decoded_samples > samples_to_decode) {
						/* in that case, count them */
						leftover_samples = decoded_samples - samples_to_decode;
						/* and put them aside for later */
						overshoot_buffer = std::vector<int16_t>(&temp_output_buffer[samples_to_decode+1], &temp_output_buffer[decoded_samples+1]);
						/* output the other samples that didn't overflow */
						memcpy(_buf, temp_output_buffer, samples_to_decode * 2);
						_buf += samples_to_decode;
					} else {
						memcpy(_buf, temp_output_buffer, decoded_samples * 2);
						_buf += decoded_samples;
					}
					
					free(temp_output_buffer);
				} else {	/* no resampling needed */
					/* overflow? (as above) */
					if (decoded_samples > samples_to_decode) {
						/* count sheep^H^H^H^H^Hsamples */
						leftover_samples = decoded_samples - samples_to_decode;
						/* and put them aside for later (mm, lamb chops) */
						overshoot_buffer = std::vector<int16_t>(&buffer[samples_to_decode+1], &buffer[decoded_samples+1]);
						/* output the other samples that didn't overflow */
						memcpy(_buf, buffer, samples_to_decode * 2);
						_buf += samples_to_decode;
					} else {
						/* just do a straight copy to buffer */
						memcpy(_buf, buffer, decoded_bytes);
						_buf += decoded_samples;
					}
				}

				samples_to_decode -= decoded_samples;
			}
		}

		av_free_packet(&packet);
	}
	
}

#endif