[SoX-devel] [PATCH] 32-bit oss support

[Eric L. <sox...@li...>]

Hi,
I recently tried playing 24-bit flac files on my RME9652 card. It 
turned out to be a hassle to get it working, since the RME9652 doesn't 
accept SND_PCM_ACCESS_RW_INTERLEAVED. I eventually got it working by 
messing with my .asoundrc, but I thought OSS ought to be working too. 
The OSS-over-ALSA emulation in Linux supports 24- and 32-bit output, 
but sox doesn't know about it. So I wrote the patch below. It's pretty 
straightforward.

I left out 24-bit support, since that just produced noise, probably 
because sox packs the samples in 3 bytes (is that true? I didn't 
check) and OSS expects them in 4 bytes. Anyway, I don't think 24-bit 
support would add any value if we have 32-bit support.

cheers,

Eric


Index: src/oss.c
===================================================================
RCS file: /cvsroot/sox/sox/src/oss.c,v
retrieving revision 1.67
diff -u -w -r1.67 oss.c
--- src/oss.c	7 Feb 2009 07:49:16 -0000	1.67
+++ src/oss.c	4 Nov 2010 19:11:19 -0000
@@ -36,6 +36,17 @@
    #include <machine/soundcard.h>
  #endif

+/* these appear in the sys/soundcard.h of OSS 4.x, and in Linux's
+ * sound/core/oss/pcm_oss.c (2.6.24 and later), but are typically
+ * not included in system header files.
+ */
+#ifndef AFMT_S32_LE
+#define AFMT_S32_LE 0x00001000
+#endif
+#ifndef AFMT_S32_BE
+#define AFMT_S32_BE 0x00002000
+#endif
+
  #include <sys/ioctl.h>

  typedef sox_fileinfo_t priv_t;
@@ -72,6 +83,21 @@
              ft->encoding.encoding = SOX_ENCODING_SIGN2;
          }
      }
+    else if (ft->encoding.bits_per_sample == 32) {
+        /* Attempt to use endian that user specified */
+        if (ft->encoding.reverse_bytes)
+            sampletype = (MACHINE_IS_BIGENDIAN) ? AFMT_S32_LE : AFMT_S32_BE;
+        else
+            sampletype = (MACHINE_IS_BIGENDIAN) ? AFMT_S32_BE : AFMT_S32_LE;
+        samplesize = 32;
+        if (ft->encoding.encoding == SOX_ENCODING_UNKNOWN)
+            ft->encoding.encoding = SOX_ENCODING_SIGN2;
+        if (ft->encoding.encoding != SOX_ENCODING_SIGN2) {
+            lsx_report("OSS driver only supports signed with words");
+            lsx_report("Forcing to signed linear");
+            ft->encoding.encoding = SOX_ENCODING_SIGN2;
+        }
+    }
      else {
          /* Attempt to use endian that user specified */
          if (ft->encoding.reverse_bytes)
@@ -199,7 +225,7 @@
  {
    static char const * const names[] = {"ossdsp", "oss", NULL};
    static unsigned const write_encodings[] = {
-    SOX_ENCODING_SIGN2, 16, 0,
+    SOX_ENCODING_SIGN2, 32, 16, 0,
      SOX_ENCODING_UNSIGNED, 8, 0,
      0};
    static sox_format_handler_t const handler = {SOX_LIB_VERSION_CODE,