Decoding AAC SCE and LFE - Revision history

Multimedia Mike: Reverted edits by QsiYqq (Talk); changed back to last version by DonDiego

2007-04-11T15:55:36Z

Reverted edits by QsiYqq (Talk); changed back to last version by DonDiego

← Older revision		Revision as of 08:55, 11 April 2007
Line 14:		Line 14:

	syntax.c:decode_sce_lfe()		syntax.c:decode_sce_lfe()
	- syntax.c:single_lfe_channel_element()		+- syntax.c:single_lfe_channel_element()
	- syntax.c:individual_channel_stream()		+- syntax.c:individual_channel_stream()
	- ''(SBR decoding stuff)''		+- ''(SBR decoding stuff)''
	- specrec.c:reconstruct_single_channel()		+- specrec.c:reconstruct_single_channel()

	== decode_sce_lfe() ==		== decode_sce_lfe() ==

QsiYqq at 15:53, 11 April 2007

2007-04-11T15:53:01Z

← Older revision		Revision as of 08:53, 11 April 2007
Line 14:		Line 14:

	syntax.c:decode_sce_lfe()		syntax.c:decode_sce_lfe()
	+- syntax.c:single_lfe_channel_element()		- syntax.c:single_lfe_channel_element()
	+- syntax.c:individual_channel_stream()		- syntax.c:individual_channel_stream()
	+- ''(SBR decoding stuff)''		- ''(SBR decoding stuff)''
	+- specrec.c:reconstruct_single_channel()		- specrec.c:reconstruct_single_channel()

	== decode_sce_lfe() ==		== decode_sce_lfe() ==

DonDiego: grammar, structure

2006-03-13T13:19:35Z

grammar, structure

← Older revision		Revision as of 06:19, 13 March 2006
Line 1:		Line 1:
	''Part of [[Understanding AAC]]''		''Part of [[Understanding AAC]]''

	An SCE is a single channel element. An LFE is a special type of SCE and may stand for low frequency element) These elements ~~contains~~ the encoded data a single audio channel. Presently, this description is only concerned with what it takes to decode low complexity (LC) data ~~and processing~~ that affects other features is skipped (except if the data needs to be parsed from the bitstream).		An SCE is a single channel element. An LFE is a special type of SCE and may stand for low frequency element. These elements contain the encoded data (a single audio channel). Presently, this description is only concerned with what it takes to decode low complexity (LC) data. Processing that affects other features is skipped (except if the data needs to be parsed from the bitstream).

	A note about the ad-hoc conventions in this syntax description: This notation:		A note about the ad-hoc conventions in this syntax description: This notation:

Multimedia Mike: add intro

2006-03-12T01:59:34Z

add intro

← Older revision		Revision as of 18:59, 11 March 2006
Line 1:		Line 1:
	''Part of [[Understanding AAC]]''		''Part of [[Understanding AAC]]''

			An SCE is a single channel element. An LFE is a special type of SCE and may stand for low frequency element) These elements contains the encoded data a single audio channel. Presently, this description is only concerned with what it takes to decode low complexity (LC) data and processing that affects other features is skipped (except if the data needs to be parsed from the bitstream).

			A note about the ad-hoc conventions in this syntax description: This notation:
			6 bits: foo
			indicates that the next 6 bits are to be read from the bitstream and stored in variable foo. Similarily, this notation:
			foo: bar
			indicates that the next (foo) quantity bits are to be read from the bitstream and stored in variable bar.

	== Function Hierarchy ==		== Function Hierarchy ==

Multimedia Mike: /* individual_channel_stream(ic_stream ics) */ add parameter

2006-03-12T01:53:19Z

individual_channel_stream(ic_stream ics): add parameter

← Older revision		Revision as of 18:53, 11 March 2006
Line 21:		Line 21:
	reconstruct_single_channel(ics, spec_data)		reconstruct_single_channel(ics, spec_data)

	== individual_channel_stream(ic_stream ics) ==		== individual_channel_stream(ic_stream ics, spec_data[1024]) ==

	This process is detailed in [[Decoding AAC CPE]].		This process is detailed in [[Decoding AAC CPE]].

	== Reconstruction ==		== Reconstruction ==

Multimedia Mike: /* decode_sce_lfe() */ code-type format, for consistency

2006-03-12T01:50:21Z

decode_sce_lfe(): code-type format, for consistency

← Older revision		Revision as of 18:50, 11 March 2006
Line 12:		Line 12:

	== decode_sce_lfe() ==		== decode_sce_lfe() ==
	single_lfe_channel_element()		single_lfe_channel_element()

	== single_lfe_channel_element() ==		== single_lfe_channel_element() ==

Multimedia Mike: /* single_lfe_channel_element() */ outline decode process

2006-03-12T01:49:54Z

single_lfe_channel_element(): outline decode process

← Older revision		Revision as of 18:49, 11 March 2006
Line 15:		Line 15:

	== single_lfe_channel_element() ==		== single_lfe_channel_element() ==
			declare an ic_stream structure: ics
			declare an array of 1024 16-bit ints for spectral data: spec_data
			4 bits: element instance tag
			individual_channel_stream(ics, spec_data)
			reconstruct_single_channel(ics, spec_data)

	== individual_channel_stream(ic_stream ics) ==		== individual_channel_stream(ic_stream ics) ==

Multimedia Mike: /* decode_sce_lfe() */

2006-03-12T01:39:15Z

decode_sce_lfe()

← Older revision		Revision as of 18:39, 11 March 2006
Line 12:		Line 12:

	== decode_sce_lfe() ==		== decode_sce_lfe() ==
			single_lfe_channel_element()

	== single_lfe_channel_element() ==		== single_lfe_channel_element() ==

Multimedia Mike: basic decoding outline

2006-03-12T01:28:51Z

basic decoding outline

New page

''Part of [[Understanding AAC]]''

== Function Hierarchy ==

When FAAD2 wants to decode a SCE or LFE, this is the sequence of functions it calls in its internal hierarchy:

syntax.c:decode_sce_lfe()
+- syntax.c:single_lfe_channel_element()
+- syntax.c:individual_channel_stream()
+- ''(SBR decoding stuff)''
+- specrec.c:reconstruct_single_channel()

== decode_sce_lfe() ==

== single_lfe_channel_element() ==

== individual_channel_stream(ic_stream ics) ==

This process is detailed in [[Decoding AAC CPE]].

== Reconstruction ==