aplay patch to add a --seek parameter

aplay patch to add a --seek parameter

[Lars Magne Ingebrigtsen]

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I'm using aplay in a sound editor to play PCM files.  But I need to be
able to say "start playing at point X" to be able to skip around in the
file.

I've used the following patch for years, but I think I forgot to submit
it for inclusion into alsa-utils.


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--- aplay.c.orig	2011-01-31 15:19:55.000000000 +0100
+++ aplay.c	2011-04-15 01:44:05.000000000 +0200
@@ -86,6 +86,7 @@
 	unsigned int rate;
 } hwparams, rhwparams;
 static int timelimit = 0;
+static int seek_length = 0;
 static int quiet_mode = 0;
 static int file_type = FORMAT_DEFAULT;
 static int open_mode = 0;
@@ -186,6 +187,7 @@
 "-c, --channels=#        channels\n"
 "-f, --format=FORMAT     sample format (case insensitive)\n"
 "-r, --rate=#            sample rate\n"
+"-S, --seek=#            seek to position # before playing\n"
 "-d, --duration=#        interrupt after # seconds\n"
 "-M, --mmap              mmap stream\n"
 "-N, --nonblock          nonblocking mode\n"
@@ -404,7 +406,7 @@
 int main(int argc, char *argv[])
 {
 	int option_index;
-	static const char short_options[] = "hnlLD:qt:c:f:r:d:MNF:A:R:T:B:vV:IPC";
+	static const char short_options[] = "hnlLD:qt:c:f:r:S:d:MNF:A:R:T:B:vV:IPC";
 	static const struct option long_options[] = {
 		{"help", 0, 0, 'h'},
 		{"version", 0, 0, OPT_VERSION},
@@ -417,6 +419,7 @@
 		{"channels", 1, 0, 'c'},
 		{"format", 1, 0, 'f'},
 		{"rate", 1, 0, 'r'},
+		{"seek", 1, 0, 'S'},
 		{"duration", 1, 0 ,'d'},
 		{"mmap", 0, 0, 'M'},
 		{"nonblock", 0, 0, 'N'},
@@ -550,6 +553,9 @@
 				return 1;
 			}
 			break;
+		case 'S':
+			seek_length = atoi(optarg);
+			break;
 		case 'd':
 			timelimit = strtol(optarg, NULL, 0);
 			break;
@@ -2457,6 +2463,8 @@
 	}
 	if (test_au(fd, audiobuf) >= 0) {
 		rhwparams.format = hwparams.format;
+		if (seek_length != 0)
+		        lseek(fd, seek_length, SEEK_SET);
 		pbrec_count = calc_count();
 		playback_go(fd, 0, pbrec_count, FORMAT_AU, name);
 		goto __end;
@@ -2468,17 +2476,23 @@
 		prg_exit(EXIT_FAILURE);;
 	}
 	if ((ofs = test_vocfile(audiobuf)) >= 0) {
+		if (seek_length != 0)
+		        lseek(fd, seek_length, SEEK_SET);
 		pbrec_count = calc_count();
 		voc_play(fd, ofs, name);
 		goto __end;
 	}
 	/* read bytes for WAVE-header */
 	if ((dtawave = test_wavefile(fd, audiobuf, dta)) >= 0) {
+		if (seek_length != 0)
+		        lseek(fd, seek_length, SEEK_SET);
 		pbrec_count = calc_count();
 		playback_go(fd, dtawave, pbrec_count, FORMAT_WAVE, name);
 	} else {
 		/* should be raw data */
 		init_raw_data();
+		if (seek_length != 0)
+		        lseek(fd, seek_length, SEEK_SET);
 		pbrec_count = calc_count();
 		playback_go(fd, dta, pbrec_count, FORMAT_RAW, name);
 	}

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-- 
(domestic pets only, the antidote for overdose, milk.)
  bloggy blog http://lars.ingebrigtsen.no/

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Re: aplay patch to add a --seek parameter

[Clemens Ladisch]

Lars Magne Ingebrigtsen wrote:
> I'm using aplay in a sound editor to play PCM files.  But I need to be
> able to say "start playing at point X" to be able to skip around in the
> file.
> 
> I've used the following patch for years, but I think I forgot to submit
> it for inclusion into alsa-utils.

Thanks.

Please provide a Signed-off-by tag, document whether this option takes
samples, frames, or (milli)seconds, and add this option to the man page.
Furthermore, the code doesn't look as if it correctly skips over chunks
in VOC files.


Regards,
Clemens

Re: aplay patch to add a --seek parameter

[Raymond Yau]

2011/4/15 Lars Magne Ingebrigtsen <larsi@gnus.org>

> I'm using aplay in a sound editor to play PCM files.  But I need to be
> able to say "start playing at point X" to be able to skip around in the
> file.
>
> I've used the following patch for years, but I think I forgot to submit
> it for inclusion into alsa-utils.
>
> it depend on X is byte or frame

when X is an odd number and the format is S16_LE , aplay just produce noise

Re: aplay patch to add a --seek parameter

[Lars Magne Ingebrigtsen]

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Clemens Ladisch <clemens@ladisch.de> writes:

> Please provide a Signed-off-by tag, document whether this option takes
> samples, frames, or (milli)seconds, and add this option to the man page.
> Furthermore, the code doesn't look as if it correctly skips over chunks
> in VOC files.

The --seek number is in bytes, so it assumes that the caller knows what
the internal structure of the file is.  For my usage (which is a simple
visual wave form editor), this makes sense, but specifying it in
milliseconds would probably be even more useful, I guess?

I'm not that familiar with the aplay internals, but so if someone who
are familiar were to transform the patch into "seek to millisecond X",
that would be nice.

Signed-off-by: Lars Magne Ingebrigtsen <larsi@gnus.org>


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--- aplay.c.orig	2011-01-31 15:19:55.000000000 +0100
+++ aplay.c	2011-04-16 02:45:43.000000000 +0200
@@ -86,6 +86,7 @@
 	unsigned int rate;
 } hwparams, rhwparams;
 static int timelimit = 0;
+static int seek_length = 0;
 static int quiet_mode = 0;
 static int file_type = FORMAT_DEFAULT;
 static int open_mode = 0;
@@ -186,6 +187,7 @@
 "-c, --channels=#        channels\n"
 "-f, --format=FORMAT     sample format (case insensitive)\n"
 "-r, --rate=#            sample rate\n"
+"-S, --seek=#            seek to position # (in bytes) before playing\n"
 "-d, --duration=#        interrupt after # seconds\n"
 "-M, --mmap              mmap stream\n"
 "-N, --nonblock          nonblocking mode\n"
@@ -404,7 +406,7 @@
 int main(int argc, char *argv[])
 {
 	int option_index;
-	static const char short_options[] = "hnlLD:qt:c:f:r:d:MNF:A:R:T:B:vV:IPC";
+	static const char short_options[] = "hnlLD:qt:c:f:r:S:d:MNF:A:R:T:B:vV:IPC";
 	static const struct option long_options[] = {
 		{"help", 0, 0, 'h'},
 		{"version", 0, 0, OPT_VERSION},
@@ -417,6 +419,7 @@
 		{"channels", 1, 0, 'c'},
 		{"format", 1, 0, 'f'},
 		{"rate", 1, 0, 'r'},
+		{"seek", 1, 0, 'S'},
 		{"duration", 1, 0 ,'d'},
 		{"mmap", 0, 0, 'M'},
 		{"nonblock", 0, 0, 'N'},
@@ -550,6 +553,9 @@
 				return 1;
 			}
 			break;
+		case 'S':
+			seek_length = atoi(optarg);
+			break;
 		case 'd':
 			timelimit = strtol(optarg, NULL, 0);
 			break;
@@ -2457,6 +2463,8 @@
 	}
 	if (test_au(fd, audiobuf) >= 0) {
 		rhwparams.format = hwparams.format;
+		if (seek_length != 0)
+		        lseek(fd, seek_length, SEEK_SET);
 		pbrec_count = calc_count();
 		playback_go(fd, 0, pbrec_count, FORMAT_AU, name);
 		goto __end;
@@ -2468,17 +2476,23 @@
 		prg_exit(EXIT_FAILURE);;
 	}
 	if ((ofs = test_vocfile(audiobuf)) >= 0) {
+		if (seek_length != 0)
+		        lseek(fd, seek_length, SEEK_SET);
 		pbrec_count = calc_count();
 		voc_play(fd, ofs, name);
 		goto __end;
 	}
 	/* read bytes for WAVE-header */
 	if ((dtawave = test_wavefile(fd, audiobuf, dta)) >= 0) {
+		if (seek_length != 0)
+		        lseek(fd, seek_length, SEEK_SET);
 		pbrec_count = calc_count();
 		playback_go(fd, dtawave, pbrec_count, FORMAT_WAVE, name);
 	} else {
 		/* should be raw data */
 		init_raw_data();
+		if (seek_length != 0)
+		        lseek(fd, seek_length, SEEK_SET);
 		pbrec_count = calc_count();
 		playback_go(fd, dta, pbrec_count, FORMAT_RAW, name);
 	}
--- aplay.1.orig	2011-04-16 02:46:57.000000000 +0200
+++ aplay.1	2011-04-16 02:49:55.000000000 +0200
@@ -77,6 +77,9 @@
 A value of zero means infinity.
 The default is zero, so if this option is omitted then the arecord process will run until it is killed.
 .TP
+\fI\-S, \-\-seek=#\fP
+Seek to position # (in bytes) before starting to play.  This option mostly makes sense on raw files.
+.TP
 \fI\-s, \-\-sleep\-min=#\fP
 Min ticks to sleep. The default is not to sleep.
 .TP

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-- 
(domestic pets only, the antidote for overdose, milk.)
  bloggy blog http://lars.ingebrigtsen.no/

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