src/mpeg.c

/*
** Copyright (C) 2019 Erik de Castro Lopo <erikd@mega-nerd.com>
** Copyright (C) 2021 Arthur Taylor <art@ified.ca>
**
** This program 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.
**
** This program 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 this program ; if not, write to the Free Software
** Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/

#include	"sfconfig.h"

#include	"sndfile.h"
#include	"common.h"

#if HAVE_MPEG

#include "mpeg.h"

static int	mpeg_write_header (SF_PRIVATE *psf, int calc_length) ;
static int	mpeg_command (SF_PRIVATE *psf, int command, void *data, int datasize) ;

/*------------------------------------------------------------------------------
 * Private functions
 */

static int
mpeg_write_header (SF_PRIVATE *psf, int UNUSED (calc_length))
{
	if (psf->have_written)
		return 0 ;

	return mpeg_l3_encoder_write_id3tag (psf) ;
}

static int
mpeg_command (SF_PRIVATE *psf, int command, void *data, int datasize)
{	int bitrate_mode ;

	switch (command)
	{	case SFC_SET_COMPRESSION_LEVEL :
			if (data == NULL || datasize != sizeof (double))
			{	psf->error = SFE_BAD_COMMAND_PARAM ;
				return SF_FALSE ;
				} ;
			if (psf->file.mode != SFM_WRITE)
			{	psf->error = SFE_NOT_WRITEMODE ;
				return SF_FALSE ;
				} ;
			return mpeg_l3_encoder_set_quality (psf, *(double *) data) ;

		case SFC_SET_BITRATE_MODE :
			if (psf->file.mode != SFM_WRITE)
			{	psf->error = SFE_NOT_WRITEMODE ;
				return SF_FALSE ;
				} ;
			if (data == NULL || datasize != sizeof (int))
			{	psf->error = SFE_BAD_COMMAND_PARAM ;
				return SF_FALSE ;
				} ;
			bitrate_mode = *(int *) data ;
			return mpeg_l3_encoder_set_bitrate_mode (psf, bitrate_mode) ;

		case SFC_GET_BITRATE_MODE :
			if (psf->file.mode == SFM_READ)
				return mpeg_decoder_get_bitrate_mode (psf) ;
			else
				return mpeg_l3_encoder_get_bitrate_mode (psf) ;

		default :
			return SF_FALSE ;
		} ;

	return SF_FALSE ;
} /* mpeg_command */

/*------------------------------------------------------------------------------
 * Public functions
 */

int
mpeg_init (SF_PRIVATE *psf, int bitrate_mode, int write_metadata)
{	int error ;

	if (psf->file.mode == SFM_RDWR)
		return SFE_BAD_MODE_RW ;

	if (psf->file.mode == SFM_WRITE)
	{	switch (SF_CODEC (psf->sf.format))
		{	case SF_FORMAT_MPEG_LAYER_III :
				if ((error = mpeg_l3_encoder_init (psf, write_metadata)))
					return error ;
				mpeg_l3_encoder_set_bitrate_mode (psf, bitrate_mode) ;
				if (write_metadata)
				{	/* ID3 support */
					psf->strings.flags = SF_STR_ALLOW_START ;
					psf->write_header = mpeg_write_header ;
					} ;
				break ;

			case SF_FORMAT_MPEG_LAYER_I :
			case SF_FORMAT_MPEG_LAYER_II :
				psf_log_printf (psf, "MPEG Layer I and II encoding is not yet supported.\n") ;
				return SFE_UNIMPLEMENTED ;

			default:
				psf_log_printf (psf, "%s: bad psf->sf.format 0x%x.\n", __func__, psf->sf.format) ;
				return SFE_INTERNAL ;
			} ;
		} ;

	if (psf->file.mode == SFM_READ)
	{	if ((error = mpeg_decoder_init (psf)))
			return error ;
		} ;

	return 0 ;
} /* mpeg_init */

int
mpeg_open (SF_PRIVATE *psf)
{	int error ;

	/* Choose variable bitrate mode by default for standalone files.*/
	if ((error = mpeg_init (psf, SF_BITRATE_MODE_VARIABLE, SF_TRUE)))
		return error ;

	psf->dataoffset = 0 ;
	psf->command = mpeg_command ;

	if (psf->filelength != SF_COUNT_MAX)
		psf->datalength = psf->filelength - psf->dataoffset ;
	else
		psf->datalength = SF_COUNT_MAX ;


	return 0 ;
} /* mpeg_open */

#else /* HAVE_MPEG */

int
mpeg_init (SF_PRIVATE *psf, int UNUSED (bitrate_mode) , int UNUSED (write_metadata))
{
	psf_log_printf (psf, "This version of libsndfile was compiled without MPEG support.\n") ;
	return SFE_UNIMPLEMENTED ;
} /* mpeg_init */

int
mpeg_open (SF_PRIVATE *psf)
{
	psf_log_printf (psf, "This version of libsndfile was compiled without MP3 support.\n") ;
	return SFE_UNIMPLEMENTED ;
} /* mpeg_open */

#endif