Simplify t_sqrt()

[ffmpeg] / libavcodec / imc.c

diff --git a/libavcodec/imc.c b/libavcodec/imc.c
index 9260b9ba2b7de3752431ae9d502b51f662481da0..934de4a6a9a18ae3e5fa12359c47d4963299dccd 100644 (file)
--- a/libavcodec/imc.c
+++ b/libavcodec/imc.c
@@ -41,6 +41,7 @@
 
 #include "imcdata.h"
 
+#define IMC_BLOCK_SIZE 64
 #define IMC_FRAME_ID 0x21
 #define BANDS 32
 #define COEFFS 256
@@ -89,7 +90,7 @@ typedef struct {
 } IMCContext;
 
 
-static int imc_decode_init(AVCodecContext * avctx)
+static av_cold int imc_decode_init(AVCodecContext * avctx)
 {
     int i, j;
     IMCContext *q = avctx->priv_data;
@@ -101,8 +102,9 @@ static int imc_decode_init(AVCodecContext * avctx)
         q->old_floor[i] = 1.0;
 
     /* Build mdct window, a simple sine window normalized with sqrt(2) */
+    ff_sine_window_init(q->mdct_sine_window, COEFFS);
     for(i = 0; i < COEFFS; i++)
-        q->mdct_sine_window[i] = sin((i + 0.5) / 512.0 * M_PI) * sqrt(2.0);
+        q->mdct_sine_window[i] *= sqrt(2.0);
     for(i = 0; i < COEFFS/2; i++){
         q->post_cos[i] = cos(i / 256.0 * M_PI);
         q->post_sin[i] = sin(i / 256.0 * M_PI);
@@ -625,7 +627,7 @@ static int imc_get_coeffs (IMCContext* q) {
 
 static int imc_decode_frame(AVCodecContext * avctx,
                             void *data, int *data_size,
-                            uint8_t * buf, int buf_size)
+                            const uint8_t * buf, int buf_size)
 {
 
     IMCContext *q = avctx->priv_data;
@@ -635,13 +637,16 @@ static int imc_decode_frame(AVCodecContext * avctx,
     int flag;
     int bits, summer;
     int counter, bitscount;
-    uint16_t *buf16 = (uint16_t *) buf;
+    uint16_t buf16[IMC_BLOCK_SIZE / 2];
 
-    /* FIXME: input should not be modified */
-    for(i = 0; i < FFMIN(buf_size, avctx->block_align) / 2; i++)
-        buf16[i] = bswap_16(buf16[i]);
+    if (buf_size < IMC_BLOCK_SIZE) {
+        av_log(avctx, AV_LOG_ERROR, "imc frame too small!\n");
+        return -1;
+    }
+    for(i = 0; i < IMC_BLOCK_SIZE / 2; i++)
+        buf16[i] = bswap_16(((const uint16_t*)buf)[i]);
 
-    init_get_bits(&q->gb, buf, 512);
+    init_get_bits(&q->gb, (const uint8_t*)buf16, IMC_BLOCK_SIZE * 8);
 
     /* Check the frame header */
     imc_hdr = get_bits(&q->gb, 9);
@@ -788,11 +793,11 @@ static int imc_decode_frame(AVCodecContext * avctx,
 
     *data_size = COEFFS * sizeof(int16_t);
 
-    return avctx->block_align;
+    return IMC_BLOCK_SIZE;
 }
 
 
-static int imc_decode_close(AVCodecContext * avctx)
+static av_cold int imc_decode_close(AVCodecContext * avctx)
 {
     IMCContext *q = avctx->priv_data;
 
@@ -809,4 +814,5 @@ AVCodec imc_decoder = {
     .init = imc_decode_init,
     .close = imc_decode_close,
     .decode = imc_decode_frame,
+    .long_name = NULL_IF_CONFIG_SMALL("IMC (Intel Music Coder)"),
 };