[FFmpeg-devel] [PATCH] doc/codecs: Add missing documentation for hwaccel_flags.

Jun Zhao mypopydev at gmail.com
Thu Jan 11 03:11:08 EET 2018



On 2018/1/11 8:45, wm4 wrote:
> On Tue, 2 Jan 2018 13:59:12 +0800
> Jun Zhao <mypopydev at gmail.com> wrote:
>
>> From e030510864c28d4b17c8d1eb09ab00f274bf5dcc Mon Sep 17 00:00:00 2001
>> From: Jun Zhao <jun.zhao at intel.com>
>> Date: Tue, 2 Jan 2018 13:55:29 +0800
>> Subject: [PATCH] doc/codecs: Add missing documentation for hwaccel_flags.
>>
>> document the hwaccel_flags option for decoding.
>>
>> Signed-off-by: Jun Zhao <jun.zhao at intel.com>
>> ---
>>  doc/codecs.texi | 27 +++++++++++++++++++++++++++
>>  1 file changed, 27 insertions(+)
>>
>> diff --git a/doc/codecs.texi b/doc/codecs.texi
>> index 7e20374334..190f03b293 100644
>> --- a/doc/codecs.texi
>> +++ b/doc/codecs.texi
>> @@ -1254,6 +1254,33 @@ ffprobe -dump_separator "
>>  Maximum number of pixels per image. This value can be used to avoid out of
>>  memory failures due to large images.
>>  
>> + at item hwaccel_flags @var{flags} (@emph{decoding,video})
>> +Set hardware accelerated decoding flags. (if active)
>> +
>> +Possible values:
>> + at table @samp
>> + at item ignore_level
>> +Ignore level, should be used for decoding even if the codec level used is unknown
>> +or higher than the maximum supported level reported by the hardware driver.
>> +
>> +It's generally a good idea to pass this flag unless you have a specific
>> +reason not to, as hardware tends to under-report supported levels.
>> + at item allow_high_depth
>> +Allow to output YUV pixel formats with a different chroma sampling than 4:2:0
>> +and/or other than 8 bits per component
>> + at item allow_profile_mismatch
> This applies only to the legacy vdpau API. (The doxygen should probably
> be updated about this.)
I think VA-API decoder used the allow_profile_mismatch.
>
> I'm not sure why stuff like this should be anywhere outside the doxygen
> in the header files?
Now ffmpeg have a hwaccel_flags option, but this option didn't have a
docs in manpage,
so I think we can document this first.
>> +Attempt to decode anyway if hardware accelerated decoder's supported profiles do not
>> +exactly match the stream.
>> +
>> +For example, this can be used to try to decode baseline profile H.264
>> +streams in hardware - it will often succeed, because many streams marked
>> +as baseline profile actually conform to constrained baseline profile.
>> +
>> +Warning: If the stream is actually not supported then the behaviour is
>> +undefined, and may include returning entirely incorrect output
>> +while indicating success.
>> + at end table
>> +
>>  @item apply_cropping @var{bool} (@emph{decoding,video})
>>  Enable cropping if cropping parameters are multiples of the required
>>  alignment for the left and top parameters. If the alignment is not met the
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