ref: 3138cb7c9a8b108a9609d53ad56ae6391130af79
parent: f82199b1047e896abadc5527a4837ede2a995ba9
author: Gregory Maxwell <[email protected]>
date: Thu Jul 11 12:36:57 EDT 2013
Doc improvements for --bitrate, and a --quality alias for it.
--- a/man/opusenc.1
+++ b/man/opusenc.1
@@ -100,15 +100,38 @@
.IP "-V, --version"
Show the version number
.IP "--bitrate N.nnn"
-Encoding bitrate in kbit/sec (6-256 per channel)
+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.
+
+.IP "--quality N.nnn"
+Target audio quality (6-256 per channel).
+
+In VBR mode this is the same as bitrate: It specifies quality in terms of the
+average rate for a large collection of audio.
.br
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 +129,8 @@
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(" --quality n.nnn Target quality (6-256/channel; same as bitrate in VBR)\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");@@ -252,6 +253,7 @@
{ {"quiet", no_argument, NULL, 0}, {"bitrate", required_argument, NULL, 0},+ {"quality", required_argument, NULL, 0}, {"hard-cbr",no_argument,NULL, 0}, {"vbr",no_argument,NULL, 0}, {"cvbr",no_argument,NULL, 0},@@ -403,7 +405,8 @@
case 0:
if(strcmp(long_options[option_index].name,"quiet")==0){quiet=1;
- }else if(strcmp(long_options[option_index].name,"bitrate")==0){+ }else if(strcmp(long_options[option_index].name,"bitrate")==0||
+ strcmp(long_options[option_index].name,"quality")==0){bitrate=atof(optarg)*1000.;
}else if(strcmp(long_options[option_index].name,"hard-cbr")==0){with_hard_cbr=1;