On 2021-07-24 03:19, Michael Niedermayer wrote:
On Sat, Jul 24, 2021 at 01:24:54AM +0530, Gyan Doshi wrote:
On 2021-07-24 01:14, Michael Niedermayer wrote:
On Fri, Jul 23, 2021 at 04:04:49PM +0530, Gyan Doshi wrote:
Currently, the user is forced to accept some noise in
packet payload, even if not requested.
---
doc/bitstream_filters.texi | 13 +++++-------
libavcodec/noise_bsf.c | 21 +++++++++++++------
tests/fate/matroska.mak | 2 +-
.../fate/matroska-mastering-display-metadata | 10 ++++-----
4 files changed, 26 insertions(+), 20 deletions(-)
diff --git a/doc/bitstream_filters.texi b/doc/bitstream_filters.texi
index d10842ae47..2b84bda1fc 100644
--- a/doc/bitstream_filters.texi
+++ b/doc/bitstream_filters.texi
@@ -534,20 +534,17 @@ container. Can be used for fuzzing or testing error
resilience/concealment.
Parameters:
@table @option
@item amount
-A numeral string, whose value is related to how often output bytes will
-be modified. Therefore, values below or equal to 0 are forbidden, and
-the lower the more frequent bytes will be modified, with 1 meaning
-every byte is modified.
+Accepts a positive integer. Lower the value, more frequently bytes will be
modified,
+with @var{1} meaning every byte is modified. Default is @var{0}.
@item dropamount
-A numeral string, whose value is related to how often packets will be dropped.
-Therefore, values below or equal to 0 are forbidden, and the lower the more
-frequent packets will be dropped, with 1 meaning every packet is dropped.
+Accepts a positive integer. Lower the value, more frequently packets will be
dropped,
+with @var{1} meaning every packet is dropped. Default is @var{0}.
@end table
The following example applies the modification to every byte but does not
drop
any packets.
@example
-ffmpeg -i INPUT -c copy -bsf noise[=1] output.mkv
+ffmpeg -i INPUT -c copy -bsf noise=amount=1 output.mkv
@end example
@section null
diff --git a/libavcodec/noise_bsf.c b/libavcodec/noise_bsf.c
index 6ebd369633..c1b0203442 100644
--- a/libavcodec/noise_bsf.c
+++ b/libavcodec/noise_bsf.c
@@ -33,20 +33,28 @@ typedef struct NoiseContext {
unsigned int state;
} NoiseContext;
-static int noise(AVBSFContext *ctx, AVPacket *pkt)
+static int noise_init(AVBSFContext *ctx)
{
NoiseContext *s = ctx->priv_data;
- int amount = s->amount > 0 ? s->amount : (s->state % 10001 + 1);
- int i, ret;
you are droping the support for variable noise
this also breaks a simple plain "-bsf noise"
Will re-add it. Is making it default required?
what else would -bsf noise do ?
Originally, noise could only alter packet data, so it made sense that
even with the default of amount=0. the filter shouldn't be a no-op,
despite the intuitive semantics of amount=0 being no alteration .
Once dropping packets was added, there can't be an expectation that with
amount=0. the user still wants to alter data. After all, the opt parser
cannot distinguish between `-bsf noise` and `-bsf
noise=amount=0[:dropamount=non-zero]`. This is how many other filters
work - the default behaviour for setpts, scale, select, crop, pad..etc
is a no-op not some arbitrary adjustment to the payload. That's not good UX.
Regards,
Gyan
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