Operating the FDK encoder in A2DP with variable bitrate mode
configuration resulted in unexpected encoder return value AACENC_ENCODE_ERROR.
Due to peak bitrate restriction the encoder quite often runs into requantization.
In case the bitrate constraint is not fulfilled, the so-called crash recovery is
used as final emergency step. The crash recovery reduces the overall bit
consumption considering the given number of bits to be saved. The bit difference
is extracted from audio element structures. In VBR mode the element wise bit
consumption state was not updated since there is typically no bitrate limitation
required.
The patch solves the choppy audio problems and increases audio quality for
AAC VBR encoding.
The changes in FDKaacEnc_QCMain() ensure that audio element bit info is always
updated. This is achieved by always calling FDKaacEnc_BitResRedistribution()
and FDKaacEnc_prepareBitDistribution() with maxBitsPerFrame variable as total
bits parameter.
Furthermore, VBR assumes a certain target bitrate which is used for internal
configuration and limitations. In case the peak bitrate parameter is less than
the VBR mode target bitrate the maximum of both bitrate configurations was used.
The function FDKaacEnc_AdjustVBRBitrateMode() is added to adjust the encoder
internal VBR mode to a desired target bitrate less than given peak bitrate.
It is possible that the peak bitrate is very close to the desired target bitrate.
The virtual available bitreservoir is quite low and the encoder would run quite
often into requantization with needless audio quality reduction. In such a
configuration, it is a better choice to use the CBR targeted threshold adaption
to avoid audio quality reduction.
In FDKaacEnc_Initialize(), there was already a bitResMode selection depending
on available bitreservoir for CBR. This selection will now also be used for VBR.
In case the bitResMode is AACENC_BR_MODE_FULL and VBR mode is selected, the VBR
threshold adaption is used. Otherwise, CBR threshold adaption strategy is used
and therefore, no unnecessary fill bits are written.
Bug: 161400526
Test: see bug
Change-Id: I1865f817180150da6add2623a64f1a102622784a
In the bug the SBR decoder has already set up 9 channels and tries to
allocate one more channel. The assignment of the QMF channels to SBR
channels fails since the QMF domain manages only 8+1 channels instead
of 10 channels as reqeusted by SBR.
Here we have added a check in sbrDecoder_InitElement() which will
return with a parse error in case additional SBR channels would exceed
the maximum number of SBR channels. This solves the potential heap
buffer overflow.
Bug: 158762825
Test: atest DecoderTestAacDrc DecoderTestAacFormat DecoderTestXheAac
Change-Id: I0150ac6d5a47ffce883010f531928656eebc619e
Merged-In: I0150ac6d5a47ffce883010f531928656eebc619e
In the bug the SBR decoder has already set up 9 channels and tries to
allocate one more channel. The assignment of the QMF channels to SBR
channels fails since the QMF domain manages only 8+1 channels instead
of 10 channels as reqeusted by SBR.
Here we have added a check in sbrDecoder_InitElement() which will
return with a parse error in case additional SBR channels would exceed
the maximum number of SBR channels. This solves the potential heap
buffer overflow.
Bug: 158762825
Test: atest DecoderTestAacDrc DecoderTestAacFormat DecoderTestXheAac
Merged-In: I0150ac6d5a47ffce883010f531928656eebc619e
Change-Id: I8569a15214707ab622e986b34b4b917251495662
In the bug the SBR decoder has already set up 9 channels and tries to
allocate one more channel. The assignment of the QMF channels to SBR
channels fails since the QMF domain manages only 8+1 channels instead
of 10 channels as reqeusted by SBR.
Here we have added a check in sbrDecoder_InitElement() which will
return with a parse error in case additional SBR channels would exceed
the maximum number of SBR channels. This solves the potential heap
buffer overflow.
Bug: 158762825
Test: atest DecoderTestAacDrc DecoderTestXheAac
Change-Id: I741f49ab3b675fa3d3217ee72e1db66b0114f7ee
Modules contributing mainline modules (APK/APEX) should set
min_sdk_version as well as apex_available.
For now setting min_sdk_version doesn't change build outputs.
But build-time checks will be added soon.
Exempt-From-Owner-Approval: cherry-pick from aosp
Bug: 152655956
Test: m
Merged-In: I662ad951a3221f967b53e7af65cb203a4b4a5e5d
Change-Id: I662ad951a3221f967b53e7af65cb203a4b4a5e5d
(cherry picked from commit d40f05a618)
Fraunhofer IIS FDK
Ray Essick
Jooyung Han
Jean-Michel Trivi
TreeHugger Robot