@@ -1,3 +1,91 @@

+/*

+ * Wmapro compatible decoder

+ * Copyright (c) 2007 Baptiste Coudurier, Benjamin Larsson, Ulion

+ * Copyright (c) 2008 - 2009 Sascha Sommer, Benjamin Larsson

+ *

+ * This file is part of FFmpeg.

+ *

+ * FFmpeg 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.

+ *

+ * FFmpeg 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 FFmpeg; if not, write to the Free Software

+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

+ */

+

+/**

+ * @file  libavcodec/wmaprodec.c

+ * @brief wmapro decoder implementation

+ * Wmapro is an MDCT based codec comparable to wma standard or AAC.

+ * The decoding therefore consists of the following steps:

+ * - bitstream decoding

+ * - reconstruction of per-channel data

+ * - rescaling and inverse quantization

+ * - IMDCT

+ * - windowing and overlapp-add

+ *

+ * The compressed wmapro bitstream is split into individual packets.

+ * Every such packet contains one or more wma frames.

+ * The compressed frames may have a variable length and frames may

+ * cross packet boundaries.

+ * Common to all wmapro frames is the number of samples that are stored in

+ * a frame.

+ * The number of samples and a few other decode flags are stored

+ * as extradata that has to be passed to the decoder.

+ *

+ * The wmapro frames themselves are again split into a variable number of

+ * subframes. Every subframe contains the data for 2^N time domain samples

+ * where N varies between 7 and 12.

+ *

+ * Example wmapro bitstream (in samples):

+ *

+ * ||   packet 0           || packet 1 || packet 2      packets

+ * ---------------------------------------------------

+ * || frame 0      || frame 1       || frame 2    ||    frames

+ * ---------------------------------------------------

+ * ||   |      |   ||   |   |   |   ||            ||    subframes of channel 0

+ * ---------------------------------------------------

+ * ||      |   |   ||   |   |   |   ||            ||    subframes of channel 1

+ * ---------------------------------------------------

+ *

+ * The frame layouts for the individual channels of a wma frame does not need

+ * to be the same.

+ *

+ * However, if the offsets and lengths of several subframes of a frame are the

+ * same, the subframes of the channels can be grouped.

+ * Every group may then use special coding techniques like M/S stereo coding

+ * to improve the compression ratio. These channel transformations do not

+ * need to be applied to a whole subframe. Instead, they can also work on

+ * individual scale factor bands (see below).

+ * The coefficients that carry the audio signal in the frequency domain

+ * are transmitted as huffman-coded vectors with 4, 2 and 1 elements.

+ * In addition to that, the encoder can switch to a runlevel coding scheme

+ * by transmitting subframe_length / 128 zero coefficients.

+ *

+ * Before the audio signal can be converted to the time domain, the

+ * coefficients have to be rescaled and inverse quantized.

+ * A subframe is therefore split into several scale factor bands that get

+ * scaled individually.

+ * Scale factors are submitted for every frame but they might be shared

+ * between the subframes of a channel. Scale factors are initially DPCM-coded.

+ * Once scale factors are shared, the differences are transmitted as runlevel

+ * codes.

+ * Every subframe length and offset combination in the frame layout shares a

+ * common quantization factor that can be adjusted for every channel by a

+ * modifier.

+ * After the inverse quantization, the coefficients get processed by an IMDCT.

+ * The resulting values are then windowed with a sine window and the first half

+ * of the values are added to the second half of the output from the previous

+ * subframe in order to reconstruct the output samples.

+ */

+

 /**

  *@brief Uninitialize the decoder and free all resources.

  *@param avctx codec context

@@ -8,11 +96,6 @@ static av_cold int decode_end(AVCodecContext *avctx)

     WMA3DecodeContext *s = avctx->priv_data;

     int i;

-    av_freep(&s->num_sfb);

-    av_freep(&s->sfb_offsets);

-    av_freep(&s->subwoofer_cutoffs);

-    av_freep(&s->sf_offsets);

-

     for (i = 0 ; i < WMAPRO_BLOCK_SIZES ; i++)

         ff_mdct_end(&s->mdct_ctx[i]);