decoded to five channels of PCM, a 5.1 AAC stream must be decoded to six channels of
PCM).
[C-2-2] Dynamic range metadata MUST be as defined in "Dynamic Range Control (DRC)" in
ISO/IEC 14496-3, and the
android.media.MediaFormat
DRC keys to configure the dynamic
range-related behaviors of the audio decoder. The AAC DRC keys were introduced in API
21,and are:
KEY_AAC_DRC_ATTENUATION_FACTOR
,
KEY_AAC_DRC_BOOST_FACTOR
,
KEY_AAC_DRC_HEAVY_COMPRESSION
,
KEY_AAC_DRC_TARGET_REFERENCE_LEVEL
and
KEY_AAC_ENCODED_TARGET_LEVEL
.
When decoding USAC audio, MPEG-D (ISO/IEC 23003-4):
[C-3-1] Loudness and DRC metadata MUST be interpreted and applied according to
MPEG-D DRC Dynamic Range Control Profile Level 1.
[C-3-2] The decoder MUST behave according to the configuration set with the following
android.media.MediaFormat
keys:
KEY_AAC_DRC_TARGET_REFERENCE_LEVEL
and
KEY_AAC_DRC_EFFECT_TYPE
.
MPEG-4 AAC, HE AAC, and HE AACv2 profile decoders:
MAY support loudness and dynamic range control using ISO/IEC 23003-4 Dynamic Range
Control Profile.
If ISO/IEC 23003-4 is supported and if both ISO/IEC 23003-4 and ISO/IEC 14496-3 metadata are
present in a decoded bitstream, then:
ISO/IEC 23003-4 metadata SHALL take precedence.
5.1.3. Audio Codecs Details
Format/Codec
Details
Supported File
Types/Container
Formats
MPEG-4 AAC
Profile
(AAC LC)
Support for mono/stereo/5.0/5.1 content with standard
sampling rates from 8 to 48 kHz.
3GPP (.3gp)
MPEG-4 (.mp4,
.m4a)
ADTS raw AAC
(.aac, ADIF not
supported)
MPEG-TS (.ts, not
seekable)
MPEG-4 HE
AAC Profile
(AAC+)
Support for mono/stereo/5.0/5.1 content with standard
sampling rates from 16 to 48 kHz.
MPEG-4 HE
AACv2
Profile
(enhanced
AAC+)
Support for mono/stereo/5.0/5.1 content with standard
sampling rates from 16 to 48 kHz.
AAC ELD
(enhanced
low delay
Support for mono/stereo content with standard sampling
rates from 16 to 48 kHz.
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