cook.c File Reference

Cook compatible decoder. More...

#include "libavutil/channel_layout.h"
#include "libavutil/lfg.h"
#include "audiodsp.h"
#include "avcodec.h"
#include "get_bits.h"
#include "bytestream.h"
#include "fft.h"
#include "internal.h"
#include "sinewin.h"
#include "unary.h"
#include "cookdata.h"

Classes
struct	cook_gains
struct	COOKSubpacket
struct	cook

Macros
#define	MONO   0x1000001
#define	STEREO   0x1000002
#define	JOINT_STEREO   0x1000003
#define	MC_COOK   0x2000000
#define	SUBBAND_SIZE   20
#define	MAX_SUBPACKETS   5
#define	DECODE_BYTES_PAD1(bytes)   (3 - ((bytes) + 3) % 4)
#define	DECODE_BYTES_PAD2(bytes)   ((bytes) % 4 + DECODE_BYTES_PAD1(2 * (bytes)))
#define	PRINT(a, b)   ff_dlog(q->avctx, " %s = %d\n", a, b);

Typedefs
typedef struct cook_gains	cook_gains
typedef struct COOKSubpacket	COOKSubpacket
typedef struct cook	COOKContext

Variables
AVCodec	ff_cook_decoder

Detailed Description

Cook compatible decoder.

Bastardization of the G.722.1 standard. This decoder handles RealNetworks, RealAudio G2 data. Cook is identified by the codec name cook in RM files.

To use this decoder, a calling application must supply the extradata bytes provided from the RM container; 8+ bytes for mono streams and 16+ for stereo streams (maybe more).

Codec technicalities (all this assume a buffer length of 1024): Cook works with several different techniques to achieve its compression. In the timedomain the buffer is divided into 8 pieces and quantized. If two neighboring pieces have different quantization index a smooth quantization curve is used to get a smooth overlap between the different pieces. To get to the transformdomain Cook uses a modulated lapped transform. The transform domain has 50 subbands with 20 elements each. This means only a maximum of 50*20=1000 coefficients are used out of the 1024 available.

Variable Documentation

ff_cook_decoder

AVCodec ff_cook_decoder

Initial value:

= {
    .name           = "cook",
    .long_name      = NULL_IF_CONFIG_SMALL("Cook / Cooker / Gecko (RealAudio G2)"),
    .type           = AVMEDIA_TYPE_AUDIO,
    .id             = AV_CODEC_ID_COOK,
    .priv_data_size = sizeof(COOKContext),
    .init           = cook_decode_init,
    .close          = cook_decode_close,
    .decode         = cook_decode_frame,
    .capabilities   = AV_CODEC_CAP_DR1,
    .sample_fmts    = (const enum AVSampleFormat[]) { AV_SAMPLE_FMT_FLTP,
                                                      AV_SAMPLE_FMT_NONE },
}