[vlc-commits] araw: refactor decoder to support byte-unaligned formats

[Rémi Denis-Courmont]

vlc | branch: master | Rémi Denis-Courmont <remi at remlab.net> | Wed Aug 17 19:35:18 2011 +0300| [e6d8827a31539016b472148dddd0b136f37d661e] | committer: Rémi Denis-Courmont

araw: refactor decoder to support byte-unaligned formats

> http://git.videolan.org/gitweb.cgi/vlc.git/?a=commit;h=e6d8827a31539016b472148dddd0b136f37d661e
---

 modules/codec/araw.c |   79 +++++++++++++++++++++++++------------------------
 1 files changed, 40 insertions(+), 39 deletions(-)

diff --git a/modules/codec/araw.c b/modules/codec/araw.c
index c441e82..73f05a3 100644
--- a/modules/codec/araw.c
+++ b/modules/codec/araw.c
@@ -71,9 +71,7 @@ static block_t *EncoderEncode( encoder_t *, aout_buffer_t * );
 
 struct decoder_sys_t
 {
-    const int16_t *p_logtos16;  /* used with m/alaw to int16_t */
-    int i_bytespersample;
-
+    void (*decode) (void *, const uint8_t *, unsigned);
     date_t end_date;
 };
 
@@ -169,6 +167,9 @@ static const int16_t alawtos16[256] =
        944,    912,   1008,    976,    816,    784,    880,    848
 };
 
+static void DecodeAlaw( void *, const uint8_t *, unsigned );
+static void DecodeUlaw( void *, const uint8_t *, unsigned );
+
 /*****************************************************************************
  * DecoderOpen: probe the decoder and return score
  *****************************************************************************/
@@ -228,7 +229,7 @@ static int DecoderOpen( vlc_object_t *p_this )
           (decoder_sys_t *)malloc(sizeof(decoder_sys_t)) ) == NULL )
         return VLC_ENOMEM;
 
-    p_sys->p_logtos16 = NULL;
+    p_sys->decode = NULL;
 
     msg_Dbg( p_dec, "samplerate:%dHz channels:%d bits/sample:%d",
              p_dec->fmt_in.audio.i_rate, p_dec->fmt_in.audio.i_channels,
@@ -273,13 +274,15 @@ static int DecoderOpen( vlc_object_t *p_this )
     else if( p_dec->fmt_in.i_codec == VLC_CODEC_ALAW )
     {
         p_dec->fmt_out.i_codec = VLC_CODEC_S16N;
-        p_sys->p_logtos16  = alawtos16;
+        p_dec->fmt_out.audio.i_bitspersample = 16;
+        p_sys->decode = DecodeAlaw;
         p_dec->fmt_in.audio.i_bitspersample = 8;
     }
     else if( p_dec->fmt_in.i_codec == VLC_CODEC_MULAW )
     {
         p_dec->fmt_out.i_codec = VLC_CODEC_S16N;
-        p_sys->p_logtos16  = ulawtos16;
+        p_dec->fmt_out.audio.i_bitspersample = 16;
+        p_sys->decode = DecodeUlaw;
         p_dec->fmt_in.audio.i_bitspersample = 8;
     }
     else
@@ -309,15 +312,8 @@ static int DecoderOpen( vlc_object_t *p_this )
         p_dec->fmt_out.audio.i_original_channels =
             p_dec->fmt_in.audio.i_original_channels;
 
-    if( p_dec->fmt_in.i_codec == VLC_CODEC_ALAW ||
-        p_dec->fmt_in.i_codec == VLC_CODEC_MULAW )
-    {
-        p_dec->fmt_out.audio.i_bitspersample = 16;
-    }
-
     date_Init( &p_sys->end_date, p_dec->fmt_out.audio.i_rate, 1 );
     date_Set( &p_sys->end_date, 0 );
-    p_sys->i_bytespersample = ( p_dec->fmt_in.audio.i_bitspersample + 7 ) / 8;
 
     p_dec->pf_decode_audio = DecodeBlock;
 
@@ -332,13 +328,10 @@ static int DecoderOpen( vlc_object_t *p_this )
 static aout_buffer_t *DecodeBlock( decoder_t *p_dec, block_t **pp_block )
 {
     decoder_sys_t *p_sys = p_dec->p_sys;
-    block_t *p_block;
-    aout_buffer_t *p_out;
-    int i_samples;
 
     if( !pp_block || !*pp_block ) return NULL;
 
-    p_block = *pp_block;
+    block_t *p_block = *pp_block;
 
     if( p_block->i_pts > VLC_TS_INVALID &&
         p_block->i_pts != date_Get( &p_sys->end_date ) )
@@ -355,19 +348,19 @@ static aout_buffer_t *DecodeBlock( decoder_t *p_dec, block_t **pp_block )
     /* Don't re-use the same pts twice */
     p_block->i_pts = VLC_TS_INVALID;
 
-    i_samples = p_block->i_buffer / p_sys->i_bytespersample /
-        p_dec->fmt_in.audio.i_channels;
-
-    if( i_samples <= 0 )
+    const unsigned framebits =
+        p_dec->fmt_in.audio.i_bitspersample * p_dec->fmt_in.audio.i_channels;
+    unsigned samples = (8 * p_block->i_buffer) / framebits;
+    if( samples == 0 )
     {
         block_Release( p_block );
         return NULL;
     }
 
     /* Create chunks of max 1024 samples */
-    i_samples = __MIN( i_samples, 1024 );
+    if( samples > 1024 ) samples = 1024;
 
-    p_out = decoder_NewAudioBuffer( p_dec, i_samples );
+    block_t *p_out = decoder_NewAudioBuffer( p_dec, samples );
     if( p_out == NULL )
     {
         block_Release( p_block );
@@ -375,30 +368,38 @@ static aout_buffer_t *DecodeBlock( decoder_t *p_dec, block_t **pp_block )
     }
 
     p_out->i_pts = date_Get( &p_sys->end_date );
-    p_out->i_length = date_Increment( &p_sys->end_date, i_samples )
+    p_out->i_length = date_Increment( &p_sys->end_date, samples )
                       - p_out->i_pts;
 
-    if( p_sys->p_logtos16 )
-    {
-        int16_t *s = (int16_t*)p_out->p_buffer;
-        unsigned int i;
-
-        for( i = 0; i < p_out->i_buffer / 2; i++ )
-        {
-            *s++ = p_sys->p_logtos16[*p_block->p_buffer++];
-            p_block->i_buffer--;
-        }
-    }
+    if( p_sys->decode != NULL )
+        p_sys->decode( p_out->p_buffer, p_block->p_buffer,
+                       samples * p_dec->fmt_in.audio.i_channels );
     else
-    {
         memcpy( p_out->p_buffer, p_block->p_buffer, p_out->i_buffer );
-        p_block->p_buffer += p_out->i_buffer;
-        p_block->i_buffer -= p_out->i_buffer;
-    }
+
+    samples = (samples * framebits) / 8;
+    p_block->p_buffer += samples;
+    p_block->i_buffer -= samples;
 
     return p_out;
 }
 
+static void DecodeAlaw( void *outp, const uint8_t *in, unsigned samples )
+{
+    int16_t *out = outp;
+
+    for( unsigned i = 0; i < samples; i++ )
+       *(out++) = alawtos16[*(in++)];
+}
+
+static void DecodeUlaw( void *outp, const uint8_t *in, unsigned samples )
+{
+    int16_t *out = outp;
+
+    for( unsigned i = 0; i < samples; i++ )
+       *(out++) = ulawtos16[*(in++)];
+}
+
 /*****************************************************************************
  * DecoderClose: decoder destruction
  *****************************************************************************/