From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ffbox0-bg.mplayerhq.hu (ffbox0-bg.ffmpeg.org [79.124.17.100]) by master.gitmailbox.com (Postfix) with ESMTP id 9330144CC1 for ; Mon, 14 Nov 2022 22:06:06 +0000 (UTC) Received: from [127.0.1.1] (localhost [127.0.0.1]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTP id EFB4968BBE4; Tue, 15 Nov 2022 00:05:57 +0200 (EET) Received: from iq.passwd.hu (iq.passwd.hu [217.27.212.140]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTP id E7F2368B103 for ; Tue, 15 Nov 2022 00:05:51 +0200 (EET) Received: from localhost (localhost [127.0.0.1]) by iq.passwd.hu (Postfix) with ESMTP id 9AB94E75E0 for ; Mon, 14 Nov 2022 23:05:49 +0100 (CET) X-Virus-Scanned: amavisd-new at passwd.hu Received: from iq.passwd.hu ([127.0.0.1]) by localhost (iq.passwd.hu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id R_LeQ5V9sZPp for ; Mon, 14 Nov 2022 23:05:45 +0100 (CET) Received: from iq (iq [217.27.212.140]) by iq.passwd.hu (Postfix) with ESMTPS id 7F2B9E75CE for ; Mon, 14 Nov 2022 23:05:44 +0100 (CET) Date: Mon, 14 Nov 2022 23:05:44 +0100 (CET) From: Marton Balint To: FFmpeg development discussions and patches In-Reply-To: <166844365819.20155.3362908166990565436@lain.khirnov.net> Message-ID: <362f6c69-b72d-447-7ab5-4a24695c58c8@passwd.hu> References: <20221113184441.1741-1-cus@passwd.hu> <20221113184441.1741-3-cus@passwd.hu> <166844365819.20155.3362908166990565436@lain.khirnov.net> MIME-Version: 1.0 Subject: Re: [FFmpeg-devel] [PATCH 3/3] avformat/electronicarts: add option to return alpha channel in the main video stream in VP6A codec X-BeenThere: ffmpeg-devel@ffmpeg.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: FFmpeg development discussions and patches List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: FFmpeg development discussions and patches Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: ffmpeg-devel-bounces@ffmpeg.org Sender: "ffmpeg-devel" Archived-At: List-Archive: List-Post: On Mon, 14 Nov 2022, Anton Khirnov wrote: > Quoting Marton Balint (2022-11-13 19:44:41) >> Signed-off-by: Marton Balint >> --- >> doc/demuxers.texi | 18 ++++++++++++++++ >> libavformat/electronicarts.c | 42 +++++++++++++++++++++++++++++++----- >> libavformat/version.h | 2 +- >> 3 files changed, 56 insertions(+), 6 deletions(-) >> >> diff --git a/doc/demuxers.texi b/doc/demuxers.texi >> index 2b6dd86c2a..f07f3f5318 100644 >> --- a/doc/demuxers.texi >> +++ b/doc/demuxers.texi >> @@ -285,6 +285,24 @@ This demuxer accepts the following option: >> >> @end table >> >> +@section ea >> + >> +Electronic Arts Multimedia format demuxer. >> + >> +This format is used by various Electronic Arts games. >> + >> +@subsection Options >> + >> +@table @option >> + >> +@item merge_alpha @var{bool} >> + >> +Normally the VP6 alpha channel (if exists) is returned as a secondary video >> +stream, > > Why? And why keep it as the default? VP6 alpha in EA format is a second VP6 encoded video stream where only the Y component is used and is interpreted as the alpha channel of the first VP6 stream. The alpha VP6 stream is muxed separately from the main VP6 stream, has its own stream headers and packet headers. In theory the two streams might not even have the same resolution (although most likely that is not something that is seen or supported in the wild), but the format is capable of doing it. Merged VP6 alpha (also known as the VP6A codec) means that a packet of the video stream contains the corresponding packet of both VP6 substreams like this: {OffsetOfAlpha, DataPacket, AlphaDataPacet} So data and alpha data of a frame is merged to a single packet, this is how VP6 video with alpha is muxed in FLV and SWF. So the first approach is more like how the demuxer sees data in the EA format, unfortunately it is different to what the FLV or SWF format expects, so - having no better place for it in the framework - I decided to do an optional format conversion in the EA demuxer. I did not want to change the default, but certainly doable if people prefer it. Regards, Marton _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe".