Fix roundoff issues in i_length.

[vlc] / modules / codec / lpcm.c

diff --git a/modules/codec/lpcm.c b/modules/codec/lpcm.c
index defcf45fcbee3fbaded1ff1906922944ab6d0c11..2d5c6126f5b2a90bf0286277a1143ad836165053 100644 (file)
--- a/modules/codec/lpcm.c
+++ b/modules/codec/lpcm.c
@@ -9,6 +9,7 @@
  *          Christophe Massiot <massiot@via.ecp.fr>
  *          Gildas Bazin <gbazin@videolan.org>
  *          Lauren Aimar <fenrir _AT_ videolan _DOT_ org >
+ *          Steinar H. Gunderson <steinar+vlc@gunderson.no>
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -108,15 +109,17 @@ struct encoder_sys_t
 
 /*
  * LPCM DVD header :
- * - frame number (8 bits)
- * - unknown (16 bits) == 0x0003 ?
- * - unknown (4 bits)
- * - current frame (4 bits)
- * - unknown (2 bits)
- * - frequency (2 bits) 0 == 48 kHz, 1 == 32 kHz, 2 == ?, 3 == ?
- * - unknown (1 bit)
+ * - number of frames in this packet (8 bits)
+ * - first access unit (16 bits) == 0x0003 ?
+ * - emphasis (1 bit)
+ * - mute (1 bit)
+ * - reserved (1 bit)
+ * - current frame (5 bits)
+ * - quantisation (2 bits) 0 == 16bps, 1 == 20bps, 2 == 24bps, 3 == illegal
+ * - frequency (2 bits) 0 == 48 kHz, 1 == 96 kHz, 2 == 44.1 kHz, 3 == 32 kHz
+ * - reserved (1 bit)
  * - number of channels - 1 (3 bits) 1 == 2 channels
- * - start code (8 bits) == 0x80
+ * - dynamic range (8 bits) 0x80 == neutral
  *
  * LPCM DVD-A header (http://dvd-audio.sourceforge.net/spec/aob.shtml)
  * - continuity counter (8 bits, clipped to 0x00-0x1f)
@@ -556,9 +559,14 @@ static block_t *EncodeFrames( encoder_t *p_enc, aout_buffer_t *p_aout_buf )
         p_sys->i_buffer_used = 0;
         i_bytes_consumed += i_consume_bytes;
 
-        p_block->i_dts = p_block->i_pts = p_aout_buf->i_pts +
+        /* We need to find i_length by means of next_pts due to possible roundoff errors. */
+        mtime_t this_pts = p_aout_buf->i_pts +
             (i * p_sys->i_frame_samples + i_start_offset) * CLOCK_FREQ / p_sys->i_rate;
-        p_block->i_length = p_sys->i_frame_samples * CLOCK_FREQ / p_sys->i_rate;
+        mtime_t next_pts = p_aout_buf->i_pts +
+            ((i + 1) * p_sys->i_frame_samples + i_start_offset) * CLOCK_FREQ / p_sys->i_rate;
+
+        p_block->i_pts = p_block->i_dts = this_pts;
+        p_block->i_length = next_pts - this_pts;
 
         if( !p_first_block )
             p_first_block = p_last_block = p_block;