[FFmpeg-user] QT ProRes 4444 w/ Alpha

[Ashkan Daie]

> 1. When trying to convert to qtrle, I do not get the alpha
> channel.

Please provide your command line including the complete,
uncut console output.

*Of course. Here it is*

*Input:*

*ffmpeg -i qt_4444_alpha.mov -vcodec qtrle rle.mov*

*Output:*
*ffmpeg version N-80234-g49b0246 Copyright (c) 2000-2016 the FFmpeg
developers*
*  built with gcc 5.3.0 (GCC)*
*  configuration: --disable-static --enable-shared --enable-gpl
--enable-version3 --disable-w32threads --enable-nvenc --enable-avisynth
--enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls
--enable-iconv --enable-libass --enable-libbluray --enable-libbs2b
--enable-libcaca --enable-libfreetype --enable-libgme --enable-libgsm
--enable-libilbc --enable-libmodplug --enable-libmfx --enable-libmp3lame
--enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg
--enable-libopus --enable-librtmp --enable-libschroedinger
--enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libtheora
--enable-libtwolame --enable-libvidstab --enable-libvo-amrwbenc
--enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp
--enable-libx264 --enable-libx265 --enable-libxavs --enable-libxvid
--enable-libzimg --enable-lzma --enable-decklink --enable-zlib*
*  libavutil      55. 24.100 / 55. 24.100*
*  libavcodec     57. 45.100 / 57. 45.100*
*  libavformat    57. 37.101 / 57. 37.101*
*  libavdevice    57.  0.101 / 57.  0.101*
*  libavfilter     6. 46.101 /  6. 46.101*
*  libswscale      4.  1.100 /  4.  1.100*
*  libswresample   2.  0.101 /  2.  0.101*
*  libpostproc    54.  0.100 / 54.  0.100*
*Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'qt_4444_alpha.mov':*
*  Metadata:*
*    major_brand     : qt*
*    minor_version   : 537199360*
*    compatible_brands: qt*
*  Duration: 00:00:15.48, start: 0.000000, bitrate: 352682 kb/s*
*    Stream #0:0(eng): Video: prores (ap4h / 0x68347061),
yuva444p10le(bt709), 1920x1080, 352140 kb/s, SAR 1:1 DAR 16:9, 29.97 fps,
29.97 tbr, 30k tbn, 30k tbc (default)*
*    Metadata:*
*      handler_name    : Apple Alias Data Handler*
*      encoder         : Apple ProRes 4444*
*      timecode        : 00:00:00;00*
*    Stream #0:1(eng): Data: none (tmcd / 0x64636D74), 0 kb/s (default)*
*    Metadata:*
*      handler_name    : Apple Alias Data Handler*
*      timecode        : 00:00:00;00*
*File 'rle.mov' already exists. Overwrite ? [y/N] y*
*[mov @ 0000000002867d80] Using AVStream.codec to pass codec parameters to
muxers is deprecated, use AVStream.codecpar instead.*
*Output #0, mov, to 'rle.mov':*
*  Metadata:*
*    major_brand     : qt*
*    minor_version   : 537199360*
*    compatible_brands: qt*
*    encoder         : Lavf57.37.101*
*    Stream #0:0(eng): Video: qtrle (rle  / 0x20656C72), argb, 1920x1080
[SAR 1:1 DAR 16:9], q=2-31, 200 kb/s, 0.03 fps, 30k tbn, 29.97 tbc
(default)*
*    Metadata:*
*      handler_name    : Apple Alias Data Handler*
*      timecode        : 00:00:00;00*
*      encoder         : Lavc57.45.100 qtrle*
*Stream mapping:*
*  Stream #0:0 -> #0:0 (prores (native) -> qtrle (native))*
*Press [q] to stop, [?] for help*
*frame=  464 fps= 14 q=-0.0 Lsize=  626763kB time=00:00:15.44
bitrate=332352.0kbits/s speed=0.456x*
*video:626758kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB
muxing overhead: 0.000813%*

> 2. When converting from QT ProRes 4444 w/ alpha to h264 I

> completely lose alpha channel.

H.264 does not support alpha.
…


> I know that h264 does not support alpha.

Then I am not sure I understand your question.
…


> I used Adobe Media Encoder w/ same source to h264 and it
> looks like it blends the alpha channel in the final output.
> Anyway I can get the same results using ffmpeg?

See the option -alphablend.

*Sorry. What I meant is that I know that h264 does not support alpha
channels. I am looking for a way to blend the alpha channel in the output.
The alphablend flag with uniform_color works like a charm!*

*Thank you for your help.*

On Thu, Jun 9, 2016 at 2:30 PM Carl Eugen Hoyos <cehoyos at ag.or.at> wrote:

> Ashkan Daie <ashkan.daie <at> gmail.com> writes:
>
> > 1. When trying to convert to qtrle, I do not get the alpha
> > channel.
>
> Please provide your command line including the complete,
> uncut console output.
>
> > 2. When converting from QT ProRes 4444 w/ alpha to h264 I
> > completely lose alpha channel.
>
> H.264 does not support alpha.
>
> > I know that h264 does not support alpha.
>
> Then I am not sure I understand your question.
>
> > I used Adobe Media Encoder w/ same source to h264 and it
> > looks like it blends the alpha channel in the final output.
> > Anyway I can get the same results using ffmpeg?
>
> See the option -alphablend.
>
> Carl Eugen
>
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