AAC decoding overlaps each frame with the previous one, so the first
frame decoded after a seek is only reliable once the frame before it has
been decoded. Opus declares its pre-roll in AVCodecParameters.seek_preroll,
AAC did not.
Have the decoder export its pre-roll, as it knows the frame length: 1024
or 960 samples, half of it for LD and ELD, and 1024 or 768 for USAC.
ELD needs three frames, as its low delay filterbank uses a window four
frames long. SBR keeps the state of the frame before, in its
filterbanks, its high-frequency generator and its gain smoothing, and
codes its envelopes and noise floors relative to the frame before, so
it needs one more frame, of twice as many output samples when it
doubles the sample rate. Without it, the first 256 samples decoded
after a seek into HE-AAC differ from continuous decoding by -36.6 dB
with one frame of pre-roll, and not at all with two.
Implicit SBR is only known once found in a frame, so the pre-roll is
raised then, as it is for USAC, whose frame length depends on its SBR
ratio. Demuxers get it through the stream probing, whatever the
container. A larger pre-roll declared by the container is kept, and the
documentation of AVCodecContext.seek_preroll now says a decoder may
raise it.
The output of an AAC-LC stream decoded after a seek has an error of
-9.5 dB in the first 1024 samples, against -85 dB elsewhere, which one
frame of pre-roll removes.
The pre-roll tests now show the declared value, for AAC in every
container, 4096 samples for HE-AAC, explicit or implicit, 2048 for SBR
that does not double the sample rate, and 1536 for ELD.
avcodec_parameters_to_context() copied AVCodecParameters.initial_padding
into both AVCodecContext.initial_padding and AVCodecContext.delay. Since
ff98352c3d, avcodec_open2() sets skip_samples from AVCodecContext.delay
for every decoder, so a decoder opened on a stream with container
priming, such as AAC in MP4, started out with that many samples pending
to be discarded.
The two are different things. initial_padding is the encoder priming at
the start of the stream, which the demuxer already attaches to the first
packet as skip-samples side data. delay is a property of the decoder
instance, which only decoders that know their own delay export in init.
Applying the container's value at open discards it from whatever the
first decoded packet turns out to be, so seeking before the first
decode drops real samples. For a mono 44.1 kHz AAC-LC file with 2048
priming, ffmpeg -ss 530 -t 10 -i in.m4a returned 439152 instead of
441000 samples, with the audio starting 1848 samples late.
Stop copying initial_padding into delay. Decoders that export a delay,
such as libopus, native opus, wma, lc3, ape and mpegh, set it
themselves and are unaffected, and decoding from the start of a stream
is unchanged since the side data carries the priming. The documentation
of AVCodecContext.delay now says it is discarded when the decoder is
opened, and points to seek_preroll for seeking.
The seek tests of AAC in MP4 and CAF now start at the requested time
instead of late by the container's priming.
Lets an encoder state which chroma sample locations it can accept, so the
caller can convert to one.
Signed-off-by: Kacper Michajłow <kasper93@gmail.com>
This RVV FDCT is ported from the AArch64 NEON implementation in
libavcodec/aarch64/fdctdsp_neon.S, which is based on libjpeg-turbo.
The original license notice is retained in the assembly file.
Requires RVV 1.0 with 64-bit element support (Zve64x) and VLEN >= 128.
Achieves approximately 3.29x speedup on SG2044 (VLEN=128).
Add FF_DCT_RVV to the public API, bump minor version, and add
Doxygen documentation.
Also:
- Fix include guard in riscv/fdct.h to match file path.
- Use AV_CPU_FLAG_RVV_I64 in automatic dispatch to avoid illegal
instruction on Zve32x-only CPUs.
Signed-off-by: yuanjia <yuan.jia@sanechips.com.cn>
Skipping prediction complements skip_idct and skip_loop_filter: with
both skip_pred and skip_idct discarding a frame, no pixel of that frame
is needed, so a decoder can drop all pixel operations and output the
frame with only its metadata valid. This allows callers to determine
timestamps, frame types and the reorder delay of a stream at a small
fraction of the cost of a full decode.
9.2.1 makes an inter neighbour unavailable for the coeff_token nC
derivation under constrained intra prediction with slice data
partitioning, and step 7 then drops it from the (nA + nB + 1) >> 1
average. JM instead treats it as available with nN = 0, so it still
contributes. Every partitioned stream in the wild comes from JM or a
derivative, so the decoder has to be able to do both.
Signed-off-by: guy-with-a-why <aaron@iterationlab.io>
In some cases there are compression and resource usage benefits from changing
certain encoder values at runtime over of closing, freeing, allocating and
initializing a whole new encoder. The most obvious case is rate control,
quality settings, and so on. As such, this commit introduces a new function
that attempts to reconfigure an opened encoder with a dictionary of options.
Private options that can be changed are flagged with the runtime AVOption flag.
Global options that can be changed, knowing that each encoder may support some
but not others and as such can't be flagged in the global AVOptions struct,
are signaled the same way through a new field in the FFCodecDefault struct.
An encoder may provide a callback function that will be called for the
reconfiguration process. Simple encoders that can work with only the AVOptions
being reset and don't require any extra steps may just let the default function
be called instead.
Signed-off-by: James Almer <jamrial@gmail.com>
Deprecated on 2025-11-01. It is removed right now despite
this being fairly recently, because users never had
a legitimate reason to touch these fields at all:
After all, their meaning was entirely undocumented.
Furthermore, the split callback is unset for any parser
since commit e5af920309 from 2021.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
The parser API was scheduled to use enum AVCodecID
in commit 8a322c956f
on 2025-11-01. The switch is made now despite this
being fairly recently because it involves no deprecation
and therefore no change from our downstreams at all.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
It is only used by the MPEG-2 encoder, so replace it
by a private option instead. Use a more elaborate term
for it: intra_dc_precision ("dc" could be anything).
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
It's a name that communicates its functionality in a better way.
Since the function was introduced very recently, we can safely rename it.
Signed-off-by: James Almer <jamrial@gmail.com>
Normally, this function tries to make sure all threads are saturated with
work to do before returning any frames; and will continue requesting packets
until that is the case.
However, this significantly slows down initial decoding latency when only
requesting a single frame (to e.g. configure the filter graph), and also
wastes a lot of unnecessary memory in the event that the user does not intend
to decode more frames until later.
By introducing a new `flags` paramater and a new flag
`AV_CODEC_RECEIVE_FRAME_FLAG_SYNCHRONOUS` to go along with it, we can allow
users to temporarily bypass this logic.
AVCodecParser has several fields which are not really meant
to be accessed by users, but it has no public-private
demarkation line, so these fields are technically public
and can therefore not simply be made private like
20f9727018 did for AVCodec.*
This commit therefore deprecates these fields and
schedules them to become private. All parsers have already
been switched to FFCodecParser, which (for now) is a union
of AVCodecParser and an unnamed clone of AVCodecParser
(new fields can be added at the end of this clone).
*: This is also the reason why split has never been removed despite
not being set for several years now.
Reviewed-by: James Almer <jamrial@gmail.com>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
Following in the footsteps of the previous commit, this commit adds the
new fields to AVCodecContext so we can start properly setting it on codecs,
as well as limiting the list of supported options to detect a format mismatch
during encode.
This commit also sets up the necessary infrastructure to start using the
newly added field in all codecs.
These properties are unreliable because they depend on the frames decoded so
far, users should check directly the presence of the decoded AVFrame side data
or AVFrame flags.
Signed-off-by: Marton Balint <cus@passwd.hu>
This replaces the myriad of existing lists in AVCodec by a unified API
call, allowing us to (ultimately) trim down the sizeof(AVCodec) quite
substantially, while also making this more trivially extensible.
In addition to the already covered lists, add two new entries for color
space and color range, mirroring the newly added negotiable fields in
libavfilter.
Once the deprecation period passes for the existing public fields, the
rough plan is to move the commonly used fields (such as
pix_fmt/sample_fmt) into FFCodec, possibly as a union of audio and video
configuration types, and then implement the rarely used fields with
custom callbacks.
The code is imported from libjpeg-turbo-3.0.1. The neon registers used
have been changed to avoid modifying v8-v15.
Reviewed-by: Martin Storsjö <martin@martin.st>
Doxygen only associates this comment with "pts_correction_num_faulty_pts",
causing it to display incorrectly.
Signed-off-by: Andrew Sayers <ffmpeg-devel@pileofstuff.org>
It used to be used with preallocated packet buffers with
the old encode API, but said API is no more and therefore
there is no reason for this to be public any more.
So deprecate it and use an internal replacement
for the encoders using it as an upper bound for the
size of their headers.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
Romain Beauxis