ref: 1ba6702095e3bf7d64e39557246e359fdd13dec4
parent: c08a77d3cd47845ee28817915f278d78ed393e8c
author: Ron <[email protected]>
date: Sat Jul 13 13:41:37 EDT 2013
Doc improvements for --bitrate. Include the doc fixes from 3138cb7c9a8b108a9609d53ad56ae6391130af79, even if people don't want the --quality alias after all.
--- a/man/opusenc.1
+++ b/man/opusenc.1
@@ -100,15 +100,33 @@
.IP "-V, --version"
Show the version number
.IP "--bitrate N.nnn"
-Encoding bitrate in kbit/sec (6-256 per channel)
-.br
+Target bitrate in kbit/sec (6-256 per channel)
+
+In VBR mode this specifies the average rate for a large and diverse
+collection of audio. In CVBR and Hard-CBR mode it specifies the specific
+output bitrate.
+
Default for >=44.1kHz input is 64kbps per mono stream, 96kbps per coupled pair.
+
.IP "--vbr"
Use variable bitrate encoding (default)
+
+In VBR mode the bitrate may go up and down freely depending on the content
+to achieve more consistent quality.
+
.IP "--cvbr"
-Use constrained variable bitrate encoding
+Use constrained variable bitrate encoding.
+
+Outputs to a specific bitrate. This mode is analogous to CBR in AAC/MP3
+encoders and managed mode in vorbis coders. This delivers less consistent
+quality than VBR mode but consistent bitrate.
.IP "--hard-cbr"
-Use hard constant bitrate encoding
+Use hard constant bitrate encoding.
+
+With hard-cbr every frame will be exactly the same size, similar to how
+speech codecs work. This delivers lower overall quality but is useful
+ where bitrate changes might leak data in encrypted channels or on
+synchronous transports.
.IP "--comp N"
Encoding computational complexity (0-10, default: 10). Zero gives the
fastest encodes but lower quality, while 10 gives the highest quality
--- a/src/opusenc.c
+++ b/src/opusenc.c
@@ -129,7 +129,7 @@
printf(" filename.opus compressed file\n");
printf(" - stdout\n");
printf("\nEncoding options:\n");
- printf(" --bitrate n.nnn Encoding bitrate in kbit/sec (6-256 per channel)\n");
+ printf(" --bitrate n.nnn Target bitrate in kbit/sec (6-256/channel)\n");
printf(" --vbr Use variable bitrate encoding (default)\n");
printf(" --cvbr Use constrained variable bitrate encoding\n");
printf(" --hard-cbr Use hard constant bitrate encoding\n");