From 05bf400a7a7ae9cd2d9fa39b8d7b8e3b6edf5c92 Mon Sep 17 00:00:00 2001 From: Ralph Giles <giles@mozilla.com> Date: Wed, 19 Dec 2012 12:21:06 -0800 Subject: [PATCH] Update ogg draft based on comments from Tina le Grand. http://www.ietf.org/mail-archive/web/codec/current/msg02951.html --- doc/draft-ietf-codec-oggopus.xml | 58 +++++++++++++++++++++++++++----- 1 file changed, 50 insertions(+), 8 deletions(-) diff --git a/doc/draft-ietf-codec-oggopus.xml b/doc/draft-ietf-codec-oggopus.xml index 9f6cbbe0f..758d6b38a 100644 --- a/doc/draft-ietf-codec-oggopus.xml +++ b/doc/draft-ietf-codec-oggopus.xml @@ -423,7 +423,8 @@ If the point 80 ms prior to the seek target comes before the initial PCM <section anchor="headers" title="Header Packets"> <t> -An Opus stream contains exactly two mandatory header packets. +An Opus stream contains exactly two mandatory header packets: + an identification header and a comment header. </t> <section anchor="id_header" title="Identification Header"> @@ -506,8 +507,9 @@ See <xref target="channel_mapping"/> for details. This is the number of samples (at 48 kHz) to discard from the decoder output when starting playback, and also the number to subtract from a page's granule position to calculate its PCM sample position. -When constructing cropped Ogg Opus streams, a pre-skip of at least - 3,840 samples (80 ms) is RECOMMENDED to ensure complete convergence. +When cropping the beginning of existing Ogg Opus streams, a pre-skip of at + least 3,840 samples (80 ms) is RECOMMENDED to ensure complete + convergence in the decoder. <vspace blankLines="1"/> </t> <t><spanx style="strong">Input Sample Rate</spanx> (32 bits, unsigned, little @@ -729,10 +731,32 @@ When the 'channel mapping family' octet has this value, the channel mapping </t> <t>Family 1 (Vorbis channel order): <vspace blankLines="1"/> -Allowed numbers of channels: 1...8.<vspace/> -Channel meanings depend on the number of channels. -See <xref target="vorbis-mapping"/> for the assignments from output channel - number to specific speaker locations. +Allowed numbers of channels: 1...8. +<vspace/> +Each channel is assigned to a speaker location in a conventional surround + configuration. +Specific locations depend on the number of channels, and are given below + in order of the corresponding channel indicies. +<list style="symbols"> + <t>1 channel: monophonic (mono).</t> + <t>2 channels: stereo (left, right).</t> + <t>3 channels: linear surround (left, center, right)</t> + <t>4 channels: quadraphonic (front left, front right, rear left, rear right).</t> + <t>5 channels: 5.0 surround (front left, center, front right, rear left, rear right).</t> + <t>6 channels: 5.1 surround (front left, center, front right, rear left, rear right, LFE).</t> + <t>7 channels: 6.1 surround (front left, center, front right, side left, side right, rear center, LFE).</t> + <t>8 channels: 7.1 surround (front left, center, front right, side left, side right, rear left, rear right, LFE)</t> +</list> +This set of surround configurations and speaker location orderings is the same + as the one used by the Vorbis codec. <xref target="vorbis-mapping"/> +The ordering is different from the one used by the + WAVE <xref target="wave-multichannel"/> and + FLAC <xref target="flac"/> formats, + although the configurations match, so correct ordering requires permutation + of the output channels when encoding from or decoding to those formats. +Implementations SHOULD identify 'side' or 'rear' speaker locations with + 'surround' as appropriate when interfacing with audio formats or systems + which prefer that terminology. <vspace blankLines="1"/> </t> <t>Family 255 (no defined channel meaning): @@ -829,7 +853,7 @@ It MUST NOT indicate that the vendor string is longer than the rest of the <vspace blankLines="1"/> This is a simple human-readable tag for vendor information, encoded as a UTF-8 string <xref target="RFC3629"/>. -No terminating NUL octet is required. +No terminating null octet is required. <vspace blankLines="1"/> This tag is intended to identify the codec encoder and encapsulation implementations, for tracing differences in technical behavior. @@ -1094,6 +1118,15 @@ The authors agree to grant third parties the irrevocable right to copy, use, <!--?rfc include="http://xml.resource.org/public/rfc/bibxml/reference.RFC.3550.xml"?--> &rfc4732; +<reference anchor="flac" + target="https://xiph.org/flac/format.html"> + <front> + <title>FLAC - Free Lossless Audio Codec Format Description</title> + <author initials="J." surname="Coalson" fullname="Josh Coalson"/> + <date month="January" year="2008"/> + </front> +</reference> + <reference anchor="replay-gain" target="http://wiki.xiph.org/VorbisComment#Replay_Gain"> <front> @@ -1126,6 +1159,15 @@ The authors agree to grant third parties the irrevocable right to copy, use, </front> </reference> +<reference anchor="wave-multichannel" + target="http://msdn.microsoft.com/en-us/windows/hardware/gg463006.aspx"> + <front> + <title>Multiple Channel Audio Data and WAVE Files</title> + <author fullname="Microsoft Corporation"/> + <date month="March" year="2007"/> + </front> +</reference> + </references> </back> -- GitLab