FFmpeg

75274 Commits

37 Branches

400 Tags

484 MiB

Tag: Branch: Tree: a0a2ca024b

Commit Graph

Author	SHA1	Message	Date
Rostislav Pehlivanov	44ddee945a	aacenc_pred: rework the way prediction is done This commit completely alters the algorithm of prediction. The original commit which introduced prediction was completely incorrect to even remotely care about what the actual coefficients contain or whether any options were enabled. Not my actual fault. This commit treats prediction the way the decoder does and expects to do: like lossy encryption. Everything related to prediction now happens at the very end but just before quantization and encoding of coefficients. On the decoder side, prediction happens before anything has had a chance to even access the coefficients. Also the original implementation had problems because it actually touched the band_type of special bands which already had their scalefactor indices marked and it's a wonder the asserion wasn't triggered when transmitting those. Overall, this now drastically increases audio quality and you should think about enabling it if you don't plan on playing anything encoded on really old low power ultra-embedded devices since they might not support decoding of prediction or AAC-Main. Though the specifications were written ages ago and as times change so do the FLOPS. Signed-off-by: Rostislav Pehlivanov <atomnuker@gmail.com>	10 years ago
Timothy Gu	21dd5279c3	aacenc: Add missing ff_ prefixes Signed-off-by: Rostislav Pehlivanov <atomnuker@gmail.com> Reviewed-by: Ganesh Ajjanagadde <gajjanag@mit.edu>	10 years ago
Rostislav Pehlivanov	76b81b10d9	aacenc: implement the complete AAC-Main profile This commit finalizes AAC-Main profile encoding support by implementing all mandatory and optional tools available in the specifications and current decoders. The AAC-Main profile reqires that prediction support be present (although decoders don't require it to be enabled) for an encoder to be deemed capable of AAC-Main encoding, as well as TNS, PNS and IS, all of which were implemented with previous commits or earlier of this year. Users are encouraged to test the new functionality using either -profile:a aac_main or -aac_pred 1, the former of which will enable the prediction option by default and the latter will change the profile to AAC-Main. No other options shall be changed by enabling either, it's currently up to the users to decide what's best. The current implementation works best using M/S and/or IS, so users are also welcome to enable both options and any other options (TNS, PNS) for maximum quality. Signed-off-by: Rostislav Pehlivanov <atomnuker@gmail.com>	10 years ago

Author

SHA1

Message

Date

Rostislav Pehlivanov

44ddee945a

aacenc_pred: rework the way prediction is done

This commit completely alters the algorithm of prediction.
The original commit which introduced prediction was completely
incorrect to even remotely care about what the actual coefficients
contain or whether any options were enabled. Not my actual fault.

This commit treats prediction the way the decoder does and expects
to do: like lossy encryption. Everything related to prediction now
happens at the very end but just before quantization and encoding
of coefficients. On the decoder side, prediction happens before
anything has had a chance to even access the coefficients.

Also the original implementation had problems because it actually
touched the band_type of special bands which already had their
scalefactor indices marked and it's a wonder the asserion wasn't
triggered when transmitting those.

Overall, this now drastically increases audio quality and you should
think about enabling it if you don't plan on playing anything encoded
on really old low power ultra-embedded devices since they might not
support decoding of prediction or AAC-Main. Though the specifications
were written ages ago and as times change so do the FLOPS.

Signed-off-by: Rostislav Pehlivanov <atomnuker@gmail.com>

10 years ago

Timothy Gu

21dd5279c3

aacenc: Add missing ff_ prefixes

Signed-off-by: Rostislav Pehlivanov <atomnuker@gmail.com>
Reviewed-by: Ganesh Ajjanagadde <gajjanag@mit.edu>

10 years ago

Rostislav Pehlivanov

76b81b10d9

aacenc: implement the complete AAC-Main profile

This commit finalizes AAC-Main profile encoding support
by implementing all mandatory and optional tools available
in the specifications and current decoders.

The AAC-Main profile reqires that prediction support be
present (although decoders don't require it to be enabled)
for an encoder to be deemed capable of AAC-Main encoding,
as well as TNS, PNS and IS, all of which were implemented
with previous commits or earlier of this year.

Users are encouraged to test the new functionality using either
-profile:a aac_main or -aac_pred 1, the former of which will enable
the prediction option by default and the latter will change the
profile to AAC-Main. No other options shall be changed by enabling
either, it's currently up to the users to decide what's best.

The current implementation works best using M/S and/or IS,
so users are also welcome to enable both options and any
other options (TNS, PNS) for maximum quality.

Signed-off-by: Rostislav Pehlivanov <atomnuker@gmail.com>

10 years ago

3 Commits (a0a2ca024bd0e6e3cd6cfa3fb878871a18a611e6)