twinvq: Split VQF-specific part from common TwinVQ decoder core

Signed-off-by: Diego Biurrun <diego@biurrun.de>

1 files changed, 26 insertions, 546 deletions

diff --git a/libavcodec/twinvq.c b/libavcodec/twinvq.c
index 419a94f666..94cc9da735 100644
--- a/libavcodec/twinvq.c
+++ b/libavcodec/twinvq.c
@@ -25,229 +25,11 @@
 #include "libavutil/channel_layout.h"
 #include "libavutil/float_dsp.h"
 #include "avcodec.h"
-#include "get_bits.h"
 #include "fft.h"
 #include "internal.h"
 #include "lsp.h"
 #include "sinewin.h"
-#include "twinvq_data.h"
-
-enum TwinVQFrameType {
-    TWINVQ_FT_SHORT = 0,  ///< Short frame  (divided in n   sub-blocks)
-    TWINVQ_FT_MEDIUM,     ///< Medium frame (divided in m<n sub-blocks)
-    TWINVQ_FT_LONG,       ///< Long frame   (single sub-block + PPC)
-    TWINVQ_FT_PPC,        ///< Periodic Peak Component (part of the long frame)
-};
-
-#define TWINVQ_PPC_SHAPE_CB_SIZE 64
-#define TWINVQ_PPC_SHAPE_LEN_MAX 60
-#define TWINVQ_SUB_AMP_MAX       4500.0
-#define TWINVQ_MULAW_MU          100.0
-#define TWINVQ_GAIN_BITS         8
-#define TWINVQ_AMP_MAX           13000.0
-#define TWINVQ_SUB_GAIN_BITS     5
-#define TWINVQ_WINDOW_TYPE_BITS  4
-#define TWINVQ_PGAIN_MU          200
-#define TWINVQ_LSP_COEFS_MAX     20
-#define TWINVQ_LSP_SPLIT_MAX     4
-#define TWINVQ_CHANNELS_MAX      2
-#define TWINVQ_SUBBLOCKS_MAX     16
-#define TWINVQ_BARK_N_COEF_MAX   4
-
-/**
- * Parameters and tables that are different for each frame type
- */
-struct TwinVQFrameMode {
-    uint8_t         sub;      ///< Number subblocks in each frame
-    const uint16_t *bark_tab;
-
-    /** number of distinct bark scale envelope values */
-    uint8_t         bark_env_size;
-
-    const int16_t  *bark_cb;    ///< codebook for the bark scale envelope (BSE)
-    uint8_t         bark_n_coef;///< number of BSE CB coefficients to read
-    uint8_t         bark_n_bit; ///< number of bits of the BSE coefs
-
-    //@{
-    /** main codebooks for spectrum data */
-    const int16_t    *cb0;
-    const int16_t    *cb1;
-    //@}
-
-    uint8_t         cb_len_read; ///< number of spectrum coefficients to read
-};
-
-typedef struct TwinVQFrameData {
-    int     window_type;
-    enum TwinVQFrameType ftype;
-
-    uint8_t main_coeffs[1024];
-    uint8_t ppc_coeffs[TWINVQ_PPC_SHAPE_LEN_MAX];
-
-    uint8_t gain_bits[TWINVQ_CHANNELS_MAX];
-    uint8_t sub_gain_bits[TWINVQ_CHANNELS_MAX * TWINVQ_SUBBLOCKS_MAX];
-
-    uint8_t bark1[TWINVQ_CHANNELS_MAX][TWINVQ_SUBBLOCKS_MAX][TWINVQ_BARK_N_COEF_MAX];
-    uint8_t bark_use_hist[TWINVQ_CHANNELS_MAX][TWINVQ_SUBBLOCKS_MAX];
-
-    uint8_t lpc_idx1[TWINVQ_CHANNELS_MAX];
-    uint8_t lpc_idx2[TWINVQ_CHANNELS_MAX][TWINVQ_LSP_SPLIT_MAX];
-    uint8_t lpc_hist_idx[TWINVQ_CHANNELS_MAX];
-
-    int     p_coef[TWINVQ_CHANNELS_MAX];
-    int     g_coef[TWINVQ_CHANNELS_MAX];
-} TwinVQFrameData;
-
-/**
- * Parameters and tables that are different for every combination of
- * bitrate/sample rate
- */
-typedef struct TwinVQModeTab {
-    struct TwinVQFrameMode fmode[3]; ///< frame type-dependant parameters
-
-    uint16_t     size;        ///< frame size in samples
-    uint8_t      n_lsp;       ///< number of lsp coefficients
-    const float *lspcodebook;
-
-    /* number of bits of the different LSP CB coefficients */
-    uint8_t      lsp_bit0;
-    uint8_t      lsp_bit1;
-    uint8_t      lsp_bit2;
-
-    uint8_t      lsp_split;      ///< number of CB entries for the LSP decoding
-    const int16_t *ppc_shape_cb; ///< PPC shape CB
-
-    /** number of the bits for the PPC period value */
-    uint8_t      ppc_period_bit;
-
-    uint8_t      ppc_shape_bit;  ///< number of bits of the PPC shape CB coeffs
-    uint8_t      ppc_shape_len;  ///< size of PPC shape CB
-    uint8_t      pgain_bit;      ///< bits for PPC gain
-
-    /** constant for peak period to peak width conversion */
-    uint16_t     peak_per2wid;
-} TwinVQModeTab;
-
-static const TwinVQModeTab mode_08_08 = {
-    {
-        { 8, bark_tab_s08_64,  10, tab.fcb08s, 1, 5, tab.cb0808s0, tab.cb0808s1, 18 },
-        { 2, bark_tab_m08_256, 20, tab.fcb08m, 2, 5, tab.cb0808m0, tab.cb0808m1, 16 },
-        { 1, bark_tab_l08_512, 30, tab.fcb08l, 3, 6, tab.cb0808l0, tab.cb0808l1, 17 }
-    },
-    512, 12, tab.lsp08, 1, 5, 3, 3, tab.shape08, 8, 28, 20, 6, 40
-};
-
-static const TwinVQModeTab mode_11_08 = {
-    {
-        { 8, bark_tab_s11_64,  10, tab.fcb11s, 1, 5, tab.cb1108s0, tab.cb1108s1, 29 },
-        { 2, bark_tab_m11_256, 20, tab.fcb11m, 2, 5, tab.cb1108m0, tab.cb1108m1, 24 },
-        { 1, bark_tab_l11_512, 30, tab.fcb11l, 3, 6, tab.cb1108l0, tab.cb1108l1, 27 }
-    },
-    512, 16, tab.lsp11, 1, 6, 4, 3, tab.shape11, 9, 36, 30, 7, 90
-};
-
-static const TwinVQModeTab mode_11_10 = {
-    {
-        { 8, bark_tab_s11_64,  10, tab.fcb11s, 1, 5, tab.cb1110s0, tab.cb1110s1, 21 },
-        { 2, bark_tab_m11_256, 20, tab.fcb11m, 2, 5, tab.cb1110m0, tab.cb1110m1, 18 },
-        { 1, bark_tab_l11_512, 30, tab.fcb11l, 3, 6, tab.cb1110l0, tab.cb1110l1, 20 }
-    },
-    512, 16, tab.lsp11, 1, 6, 4, 3, tab.shape11, 9, 36, 30, 7, 90
-};
-
-static const TwinVQModeTab mode_16_16 = {
-    {
-        { 8, bark_tab_s16_128,  10, tab.fcb16s, 1, 5, tab.cb1616s0, tab.cb1616s1, 16 },
-        { 2, bark_tab_m16_512,  20, tab.fcb16m, 2, 5, tab.cb1616m0, tab.cb1616m1, 15 },
-        { 1, bark_tab_l16_1024, 30, tab.fcb16l, 3, 6, tab.cb1616l0, tab.cb1616l1, 16 }
-    },
-    1024, 16, tab.lsp16, 1, 6, 4, 3, tab.shape16, 9, 56, 60, 7, 180
-};
-
-static const TwinVQModeTab mode_22_20 = {
-    {
-        { 8, bark_tab_s22_128,  10, tab.fcb22s_1, 1, 6, tab.cb2220s0, tab.cb2220s1, 18 },
-        { 2, bark_tab_m22_512,  20, tab.fcb22m_1, 2, 6, tab.cb2220m0, tab.cb2220m1, 17 },
-        { 1, bark_tab_l22_1024, 32, tab.fcb22l_1, 4, 6, tab.cb2220l0, tab.cb2220l1, 18 }
-    },
-    1024, 16, tab.lsp22_1, 1, 6, 4, 3, tab.shape22_1, 9, 56, 36, 7, 144
-};
-
-static const TwinVQModeTab mode_22_24 = {
-    {
-        { 8, bark_tab_s22_128,  10, tab.fcb22s_1, 1, 6, tab.cb2224s0, tab.cb2224s1, 15 },
-        { 2, bark_tab_m22_512,  20, tab.fcb22m_1, 2, 6, tab.cb2224m0, tab.cb2224m1, 14 },
-        { 1, bark_tab_l22_1024, 32, tab.fcb22l_1, 4, 6, tab.cb2224l0, tab.cb2224l1, 15 }
-    },
-    1024, 16, tab.lsp22_1, 1, 6, 4, 3, tab.shape22_1, 9, 56, 36, 7, 144
-};
-
-static const TwinVQModeTab mode_22_32 = {
-    {
-        { 4, bark_tab_s22_128, 10, tab.fcb22s_2, 1, 6, tab.cb2232s0, tab.cb2232s1, 11 },
-        { 2, bark_tab_m22_256, 20, tab.fcb22m_2, 2, 6, tab.cb2232m0, tab.cb2232m1, 11 },
-        { 1, bark_tab_l22_512, 32, tab.fcb22l_2, 4, 6, tab.cb2232l0, tab.cb2232l1, 12 }
-    },
-    512, 16, tab.lsp22_2, 1, 6, 4, 4, tab.shape22_2, 9, 56, 36, 7, 72
-};
-
-static const TwinVQModeTab mode_44_40 = {
-    {
-        { 16, bark_tab_s44_128,  10, tab.fcb44s, 1, 6, tab.cb4440s0, tab.cb4440s1, 18 },
-        { 4,  bark_tab_m44_512,  20, tab.fcb44m, 2, 6, tab.cb4440m0, tab.cb4440m1, 17 },
-        { 1,  bark_tab_l44_2048, 40, tab.fcb44l, 4, 6, tab.cb4440l0, tab.cb4440l1, 17 }
-    },
-    2048, 20, tab.lsp44, 1, 6, 4, 4, tab.shape44, 9, 84, 54, 7, 432
-};
-
-static const TwinVQModeTab mode_44_48 = {
-    {
-        { 16, bark_tab_s44_128,  10, tab.fcb44s, 1, 6, tab.cb4448s0, tab.cb4448s1, 15 },
-        { 4,  bark_tab_m44_512,  20, tab.fcb44m, 2, 6, tab.cb4448m0, tab.cb4448m1, 14 },
-        { 1,  bark_tab_l44_2048, 40, tab.fcb44l, 4, 6, tab.cb4448l0, tab.cb4448l1, 14 }
-    },
-    2048, 20, tab.lsp44, 1, 6, 4, 4, tab.shape44, 9, 84, 54, 7, 432
-};
-
-typedef struct TwinVQContext {
-    AVCodecContext *avctx;
-    AVFloatDSPContext fdsp;
-    FFTContext mdct_ctx[3];
-
-    const TwinVQModeTab *mtab;
-
-    // history
-    float lsp_hist[2][20];           ///< LSP coefficients of the last frame
-    float bark_hist[3][2][40];       ///< BSE coefficients of last frame
-
-    // bitstream parameters
-    int16_t permut[4][4096];
-    uint8_t length[4][2];            ///< main codebook stride
-    uint8_t length_change[4];
-    uint8_t bits_main_spec[2][4][2]; ///< bits for the main codebook
-    int bits_main_spec_change[4];
-    int n_div[4];
-
-    float *spectrum;
-    float *curr_frame;               ///< non-interleaved output
-    float *prev_frame;               ///< non-interleaved previous frame
-    int last_block_pos[2];
-    int discarded_packets;
-
-    float *cos_tabs[3];
-
-    // scratch buffers
-    float *tmp_buf;
-
-    TwinVQFrameData bits;
-} TwinVQContext;
-
-/** @note not speed critical, hence not optimized */
-static void memset_float(float *buf, float val, int size)
-{
-    while (size--)
-        *buf++ = val;
-}
+#include "twinvq.h"
 
 /**
  * Evaluate a single LPC amplitude spectrum envelope coefficient from the line
@@ -378,7 +160,8 @@ static void eval_lpcenv_2parts(TwinVQContext *tctx, enum TwinVQFrameType ftype,
     interpolate(lpc + size / 2 - step + 1, lpc[size / 2],
                 lpc[size / 2 - step], step);
 
-    memset_float(lpc + size - 2 * step + 1, lpc[size - 2 * step], 2 * step - 1);
+    twinvq_memset_float(lpc + size - 2 * step + 1, lpc[size - 2 * step],
+                        2 * step - 1);
 }
 
 /**
@@ -428,104 +211,6 @@ static void dequant(TwinVQContext *tctx, const uint8_t *cb_bits, float *out,
     }
 }
 
-static inline float mulawinv(float y, float clip, float mu)
-{
-    y = av_clipf(y / clip, -1, 1);
-    return clip * FFSIGN(y) * (exp(log(1 + mu) * fabs(y)) - 1) / mu;
-}
-
-/**
- * Evaluate a * b / 400 rounded to the nearest integer. When, for example,
- * a * b == 200 and the nearest integer is ill-defined, use a table to emulate
- * the following broken float-based implementation used by the binary decoder:
- *
- * @code
- * static int very_broken_op(int a, int b)
- * {
- *    static float test; // Ugh, force gcc to do the division first...
- *
- *    test = a / 400.0;
- *    return b * test + 0.5;
- * }
- * @endcode
- *
- * @note if this function is replaced by just ROUNDED_DIV(a * b, 400.0), the
- * stddev between the original file (before encoding with Yamaha encoder) and
- * the decoded output increases, which leads one to believe that the encoder
- * expects exactly this broken calculation.
- */
-static int very_broken_op(int a, int b)
-{
-    int x = a * b + 200;
-    int size;
-    const uint8_t *rtab;
-
-    if (x % 400 || b % 5)
-        return x / 400;
-
-    x /= 400;
-
-    size = tabs[b / 5].size;
-    rtab = tabs[b / 5].tab;
-    return x - rtab[size * av_log2(2 * (x - 1) / size) + (x - 1) % size];
-}
-
-/**
- * Sum to data a periodic peak of a given period, width and shape.
- *
- * @param period the period of the peak divised by 400.0
- */
-static void add_peak(int period, int width, const float *shape,
-                     float ppc_gain, float *speech, int len)
-{
-    int i, j;
-
-    const float *shape_end = shape + len;
-    int center;
-
-    // First peak centered around zero
-    for (i = 0; i < width / 2; i++)
-        speech[i] += ppc_gain * *shape++;
-
-    for (i = 1; i < ROUNDED_DIV(len, width); i++) {
-        center = very_broken_op(period, i);
-        for (j = -width / 2; j < (width + 1) / 2; j++)
-            speech[j + center] += ppc_gain * *shape++;
-    }
-
-    // For the last block, be careful not to go beyond the end of the buffer
-    center = very_broken_op(period, i);
-    for (j = -width / 2; j < (width + 1) / 2 && shape < shape_end; j++)
-        speech[j + center] += ppc_gain * *shape++;
-}
-
-static void decode_ppc(TwinVQContext *tctx, int period_coef,
-                       const float *shape, float ppc_gain, float *speech)
-{
-    const TwinVQModeTab *mtab = tctx->mtab;
-    int isampf = tctx->avctx->sample_rate /  1000;
-    int ibps   = tctx->avctx->bit_rate    / (1000 * tctx->avctx->channels);
-    int min_period   = ROUNDED_DIV(40 * 2 * mtab->size, isampf);
-    int max_period   = ROUNDED_DIV(40 * 2 * mtab->size * 6, isampf);
-    int period_range = max_period - min_period;
-
-    // This is actually the period multiplied by 400. It is just linearly coded
-    // between its maximum and minimum value.
-    int period = min_period +
-                 ROUNDED_DIV(period_coef * period_range,
-                             (1 << mtab->ppc_period_bit) - 1);
-    int width;
-
-    if (isampf == 22 && ibps == 32) {
-        // For some unknown reason, NTT decided to code this case differently...
-        width = ROUNDED_DIV((period + 800) * mtab->peak_per2wid,
-                            400 * mtab->size);
-    } else
-        width = period * mtab->peak_per2wid / (400 * mtab->size);
-
-    add_peak(period, width, shape, ppc_gain, speech, mtab->ppc_shape_len);
-}
-
 static void dec_gain(TwinVQContext *tctx,
                      enum TwinVQFrameType ftype, float *out)
 {
@@ -539,19 +224,19 @@ static void dec_gain(TwinVQContext *tctx,
     if (ftype == TWINVQ_FT_LONG) {
         for (i = 0; i < tctx->avctx->channels; i++)
             out[i] = (1.0 / (1 << 13)) *
-                     mulawinv(step * 0.5 + step * bits->gain_bits[i],
-                              TWINVQ_AMP_MAX, TWINVQ_MULAW_MU);
+                     twinvq_mulawinv(step * 0.5 + step * bits->gain_bits[i],
+                                     TWINVQ_AMP_MAX, TWINVQ_MULAW_MU);
     } else {
         for (i = 0; i < tctx->avctx->channels; i++) {
             float val = (1.0 / (1 << 23)) *
-                        mulawinv(step * 0.5 + step * bits->gain_bits[i],
-                                 TWINVQ_AMP_MAX, TWINVQ_MULAW_MU);
+                        twinvq_mulawinv(step * 0.5 + step * bits->gain_bits[i],
+                                        TWINVQ_AMP_MAX, TWINVQ_MULAW_MU);
 
             for (j = 0; j < sub; j++)
                 out[i * sub + j] =
-                    val * mulawinv(sub_step * 0.5 +
-                                   sub_step * bits->sub_gain_bits[i * sub + j],
-                                   TWINVQ_SUB_AMP_MAX, TWINVQ_MULAW_MU);
+                    val * twinvq_mulawinv(sub_step * 0.5 +
+                                          sub_step * bits->sub_gain_bits[i * sub + j],
+                                          TWINVQ_SUB_AMP_MAX, TWINVQ_MULAW_MU);
         }
     }
 }
@@ -721,34 +406,6 @@ static void imdct_output(TwinVQContext *tctx, enum TwinVQFrameType ftype,
     }
 }
 
-static void dec_bark_env(TwinVQContext *tctx, const uint8_t *in, int use_hist,
-                         int ch, float *out, float gain,
-                         enum TwinVQFrameType ftype)
-{
-    const TwinVQModeTab *mtab = tctx->mtab;
-    int i, j;
-    float *hist     = tctx->bark_hist[ftype][ch];
-    float val       = ((const float []) { 0.4, 0.35, 0.28 })[ftype];
-    int bark_n_coef = mtab->fmode[ftype].bark_n_coef;
-    int fw_cb_len   = mtab->fmode[ftype].bark_env_size / bark_n_coef;
-    int idx         = 0;
-
-    for (i = 0; i < fw_cb_len; i++)
-        for (j = 0; j < bark_n_coef; j++, idx++) {
-            float tmp2 = mtab->fmode[ftype].bark_cb[fw_cb_len * in[j] + i] *
-                         (1.0 / 4096);
-            float st   = use_hist ? (1.0 - val) * tmp2 + val * hist[idx] + 1.0
-                                  : tmp2 + 1.0;
-
-            hist[idx] = tmp2;
-            if (st < -1.0)
-                st = 1.0;
-
-            memset_float(out, st * gain, mtab->fmode[ftype].bark_tab[idx]);
-            out += mtab->fmode[ftype].bark_tab[idx];
-        }
-}
-
 static void read_and_decode_spectrum(TwinVQContext *tctx, float *out,
                                      enum TwinVQFrameType ftype)
 {
@@ -782,24 +439,18 @@ static void read_and_decode_spectrum(TwinVQContext *tctx, float *out,
         float lsp[TWINVQ_LSP_COEFS_MAX];
 
         for (j = 0; j < sub; j++) {
-            dec_bark_env(tctx, bits->bark1[i][j], bits->bark_use_hist[i][j], i,
-                         tctx->tmp_buf, gain[sub * i + j], ftype);
+            tctx->dec_bark_env(tctx, bits->bark1[i][j],
+                               bits->bark_use_hist[i][j], i,
+                               tctx->tmp_buf, gain[sub * i + j], ftype);
 
             tctx->fdsp.vector_fmul(chunk + block_size * j,
                                    chunk + block_size * j,
                                    tctx->tmp_buf, block_size);
         }
 
-        if (ftype == TWINVQ_FT_LONG) {
-            float pgain_step = 25000.0 / ((1 << mtab->pgain_bit) - 1);
-            float v          = 1.0 / 8192 *
-                               mulawinv(pgain_step * bits->g_coef[i] +
-                                        pgain_step / 2,
-                                        25000.0, TWINVQ_PGAIN_MU);
-
-            decode_ppc(tctx, bits->p_coef[i],
-                       ppc_shape + i * mtab->ppc_shape_len, v, chunk);
-        }
+        if (ftype == TWINVQ_FT_LONG)
+            tctx->decode_ppc(tctx, bits->p_coef[i], bits->g_coef[i],
+                             ppc_shape + i * mtab->ppc_shape_len, chunk);
 
         decode_lsp(tctx, bits->lpc_idx1[i], bits->lpc_idx2[i],
                    bits->lpc_hist_idx[i], lsp, tctx->lsp_hist[i]);
@@ -813,94 +464,14 @@ static void read_and_decode_spectrum(TwinVQContext *tctx, float *out,
     }
 }
 
-static void read_cb_data(TwinVQContext *tctx, GetBitContext *gb,
-                         uint8_t *dst, enum TwinVQFrameType ftype)
-{
-    int i;
-
-    for (i = 0; i < tctx->n_div[ftype]; i++) {
-        int bs_second_part = (i >= tctx->bits_main_spec_change[ftype]);
-
-        *dst++ = get_bits(gb, tctx->bits_main_spec[0][ftype][bs_second_part]);
-        *dst++ = get_bits(gb, tctx->bits_main_spec[1][ftype][bs_second_part]);
-    }
-}
-
-static const enum TwinVQFrameType wtype_to_ftype_table[] = {
+const enum TwinVQFrameType ff_twinvq_wtype_to_ftype_table[] = {
     TWINVQ_FT_LONG,   TWINVQ_FT_LONG, TWINVQ_FT_SHORT, TWINVQ_FT_LONG,
     TWINVQ_FT_MEDIUM, TWINVQ_FT_LONG, TWINVQ_FT_LONG,  TWINVQ_FT_MEDIUM,
     TWINVQ_FT_MEDIUM
 };
 
-static int twinvq_read_bitstream(AVCodecContext *avctx, TwinVQContext *tctx,
-                                 const uint8_t *buf, int buf_size)
-{
-    TwinVQFrameData     *bits = &tctx->bits;
-    const TwinVQModeTab *mtab = tctx->mtab;
-    int channels              = tctx->avctx->channels;
-    int sub;
-    GetBitContext gb;
-    int i, j, k;
-
-    init_get_bits(&gb, buf, buf_size * 8);
-    skip_bits(&gb, get_bits(&gb, 8));
-
-    bits->window_type = get_bits(&gb, TWINVQ_WINDOW_TYPE_BITS);
-
-    if (bits->window_type > 8) {
-        av_log(avctx, AV_LOG_ERROR, "Invalid window type, broken sample?\n");
-        return AVERROR_INVALIDDATA;
-    }
-
-    bits->ftype = wtype_to_ftype_table[tctx->bits.window_type];
-
-    sub = mtab->fmode[bits->ftype].sub;
-
-    read_cb_data(tctx, &gb, bits->main_coeffs, bits->ftype);
-
-    for (i = 0; i < channels; i++)
-        for (j = 0; j < sub; j++)
-            for (k = 0; k < mtab->fmode[bits->ftype].bark_n_coef; k++)
-                bits->bark1[i][j][k] =
-                    get_bits(&gb, mtab->fmode[bits->ftype].bark_n_bit);
-
-    for (i = 0; i < channels; i++)
-        for (j = 0; j < sub; j++)
-            bits->bark_use_hist[i][j] = get_bits1(&gb);
-
-    if (bits->ftype == TWINVQ_FT_LONG) {
-        for (i = 0; i < channels; i++)
-            bits->gain_bits[i] = get_bits(&gb, TWINVQ_GAIN_BITS);
-    } else {
-        for (i = 0; i < channels; i++) {
-            bits->gain_bits[i] = get_bits(&gb, TWINVQ_GAIN_BITS);
-            for (j = 0; j < sub; j++)
-                bits->sub_gain_bits[i * sub + j] =
-                    get_bits(&gb, TWINVQ_SUB_GAIN_BITS);
-        }
-    }
-
-    for (i = 0; i < channels; i++) {
-        bits->lpc_hist_idx[i] = get_bits(&gb, mtab->lsp_bit0);
-        bits->lpc_idx1[i]     = get_bits(&gb, mtab->lsp_bit1);
-
-        for (j = 0; j < mtab->lsp_split; j++)
-            bits->lpc_idx2[i][j] = get_bits(&gb, mtab->lsp_bit2);
-    }
-
-    if (bits->ftype == TWINVQ_FT_LONG) {
-        read_cb_data(tctx, &gb, bits->ppc_coeffs, 3);
-        for (i = 0; i < channels; i++) {
-            bits->p_coef[i] = get_bits(&gb, mtab->ppc_period_bit);
-            bits->g_coef[i] = get_bits(&gb, mtab->pgain_bit);
-        }
-    }
-
-    return 0;
-}
-
-static int twinvq_decode_frame(AVCodecContext *avctx, void *data,
-                               int *got_frame_ptr, AVPacket *avpkt)
+int ff_twinvq_decode_frame(AVCodecContext *avctx, void *data,
+                           int *got_frame_ptr, AVPacket *avpkt)
 {
     AVFrame *frame     = data;
     const uint8_t *buf = avpkt->data;
@@ -910,12 +481,6 @@ static int twinvq_decode_frame(AVCodecContext *avctx, void *data,
     float **out = NULL;
     int ret;
 
-    if (buf_size * 8 < avctx->bit_rate * mtab->size / avctx->sample_rate + 8) {
-        av_log(avctx, AV_LOG_ERROR,
-               "Frame too small (%d bytes). Truncated file?\n", buf_size);
-        return AVERROR(EINVAL);
-    }
-
     /* get output buffer */
     if (tctx->discarded_packets >= 2) {
         frame->nb_samples = mtab->size;
@@ -926,7 +491,7 @@ static int twinvq_decode_frame(AVCodecContext *avctx, void *data,
         out = (float **)frame->extended_data;
     }
 
-    if ((ret = twinvq_read_bitstream(avctx, tctx, buf, buf_size)) < 0)
+    if ((ret = tctx->read_bitstream(avctx, tctx, buf, buf_size)) < 0)
         return ret;
 
     read_and_decode_spectrum(tctx, tctx->spectrum, tctx->bits.ftype);
@@ -1162,7 +727,7 @@ static av_cold void init_bitstream_params(TwinVQContext *tctx)
         construct_perm_table(tctx, frametype);
 }
 
-static av_cold int twinvq_decode_close(AVCodecContext *avctx)
+av_cold int ff_twinvq_decode_close(AVCodecContext *avctx)
 {
     TwinVQContext *tctx = avctx->priv_data;
     int i;
@@ -1180,109 +745,24 @@ static av_cold int twinvq_decode_close(AVCodecContext *avctx)
     return 0;
 }
 
-static av_cold int twinvq_decode_init(AVCodecContext *avctx)
+av_cold int ff_twinvq_decode_init(AVCodecContext *avctx)
 {
-    int ret, isampf, ibps;
+    int ret;
     TwinVQContext *tctx = avctx->priv_data;
 
     tctx->avctx       = avctx;
     avctx->sample_fmt = AV_SAMPLE_FMT_FLTP;
 
-    if (!avctx->extradata || avctx->extradata_size < 12) {
-        av_log(avctx, AV_LOG_ERROR, "Missing or incomplete extradata\n");
-        return AVERROR_INVALIDDATA;
-    }
-    avctx->channels = AV_RB32(avctx->extradata)     + 1;
-    avctx->bit_rate = AV_RB32(avctx->extradata + 4) * 1000;
-    isampf          = AV_RB32(avctx->extradata + 8);
-
-    if (isampf < 8 || isampf > 44) {
-        av_log(avctx, AV_LOG_ERROR, "Unsupported sample rate\n");
-        return AVERROR_INVALIDDATA;
-    }
-    switch (isampf) {
-    case 44:
-        avctx->sample_rate = 44100;
-        break;
-    case 22:
-        avctx->sample_rate = 22050;
-        break;
-    case 11:
-        avctx->sample_rate = 11025;
-        break;
-    default:
-        avctx->sample_rate = isampf * 1000;
-        break;
-    }
-
-    if (avctx->channels <= 0 || avctx->channels > TWINVQ_CHANNELS_MAX) {
-        av_log(avctx, AV_LOG_ERROR, "Unsupported number of channels: %i\n",
-               avctx->channels);
-        return -1;
-    }
-    avctx->channel_layout = avctx->channels == 1 ? AV_CH_LAYOUT_MONO
-                                                 : AV_CH_LAYOUT_STEREO;
-
-    ibps = avctx->bit_rate / (1000 * avctx->channels);
-
-    switch ((isampf << 8) + ibps) {
-    case (8 << 8) + 8:
-        tctx->mtab = &mode_08_08;
-        break;
-    case (11 << 8) + 8:
-        tctx->mtab = &mode_11_08;
-        break;
-    case (11 << 8) + 10:
-        tctx->mtab = &mode_11_10;
-        break;
-    case (16 << 8) + 16:
-        tctx->mtab = &mode_16_16;
-        break;
-    case (22 << 8) + 20:
-        tctx->mtab = &mode_22_20;
-        break;
-    case (22 << 8) + 24:
-        tctx->mtab = &mode_22_24;
-        break;
-    case (22 << 8) + 32:
-        tctx->mtab = &mode_22_32;
-        break;
-    case (44 << 8) + 40:
-        tctx->mtab = &mode_44_40;
-        break;
-    case (44 << 8) + 48:
-        tctx->mtab = &mode_44_48;
-        break;
-    default:
-        av_log(avctx, AV_LOG_ERROR,
-               "This version does not support %d kHz - %d kbit/s/ch mode.\n",
-               isampf, isampf);
-        return -1;
-    }
-
     avpriv_float_dsp_init(&tctx->fdsp, avctx->flags & CODEC_FLAG_BITEXACT);
     if ((ret = init_mdct_win(tctx))) {
         av_log(avctx, AV_LOG_ERROR, "Error initializing MDCT\n");
-        twinvq_decode_close(avctx);
+        ff_twinvq_decode_close(avctx);
         return ret;
     }
     init_bitstream_params(tctx);
 
-    memset_float(tctx->bark_hist[0][0], 0.1, FF_ARRAY_ELEMS(tctx->bark_hist));
+    twinvq_memset_float(tctx->bark_hist[0][0], 0.1,
+                        FF_ARRAY_ELEMS(tctx->bark_hist));
 
     return 0;
 }
-
-AVCodec ff_twinvq_decoder = {
-    .name           = "twinvq",
-    .type           = AVMEDIA_TYPE_AUDIO,
-    .id             = AV_CODEC_ID_TWINVQ,
-    .priv_data_size = sizeof(TwinVQContext),
-    .init           = twinvq_decode_init,
-    .close          = twinvq_decode_close,
-    .decode         = twinvq_decode_frame,
-    .capabilities   = CODEC_CAP_DR1,
-    .long_name      = NULL_IF_CONFIG_SMALL("VQF TwinVQ"),
-    .sample_fmts    = (const enum AVSampleFormat[]) { AV_SAMPLE_FMT_FLTP,
-                                                      AV_SAMPLE_FMT_NONE },
-};