If you are converting to RGBA then you need to add one byte per pixel for alpha as well.
Salsaman. http://lives.sourceforge.net https://www.ohloh.net/accounts/salsaman On Wed, Aug 10, 2011 at 12:12 PM, Hinchcliffe.Mark < mark.hinchcli...@barcrestgroup.com> wrote: > Hello all,**** > > ** ** > > I am trying to decode a video of an animated star cascade (for the time > being foregoing alpha, **** > > as mentioned in my previous email to the developer mail list entitled > “Schroedinger Decoding”).**** > > ** ** > > At an arbitrary time the output shown in VLC version 1.1.11 is this image: > **** > > http://img405.imageshack.us/img405/268/vlcouput.png**** > > ** ** > > As the video progresses the stars fall down the screen.**** > > ** ** > > Currently my Schroedinger decoder produces the following image:**** > > http://img200.imageshack.us/img200/1306/decoderoutput.png**** > > ** ** > > As my decoder outputs the frames to the display texture the horizontal > lines move down the screen.**** > > ** ** > > I am hoping someone has come across output like this in their experiments > and can provide me some insight as to why my display texture should contain > what amounts to garbage.**** > > ** ** > > - We know the file is good because it works in vlc. – Perhaps VLC uses > DiracResearch or an older version of Schroedinger?**** > > - I believe the decoding process is working correctly at least to some > degree because I can decode the entire file and schroedingers state > transitions appear sensible.**** > > - I believe the issue may lie in either my method of conversion from > YUV420p to RGBA32, **** > > or at some random point the texture I am altering with the schroedinger > decoded frame data is receiving garbled data, perhaps a buffer overrun or > some scoping issue or stray delete’s.**** > > ** ** > > The code I am using for YUV420p to RGBA32 conversion:**** > > // HDTV: Constants for YCbCr conversion to RGBA**** > > //const double wr = 0.2126;**** > > //const double wb = 0.0722;**** > > //const double wg = 1 - wr - wb;**** > > //// SDTV: Constants for YCbCr conversion to RGBA**** > > //// http://en.wikipedia.org/wiki/YUV#Conversion_to.2Ffrom_RGB**** > > const double wr = 0.299;**** > > const double wb = 0.114;**** > > const double wg = 0.587;**** > > double EY = CLAMP( (double)*Y, luma_offset, luma_offset + luma_excursion > );**** > > double ECb = CLAMP( (double)*U, chroma_offset - chroma_excursion / 2.0, > chroma_offset + chroma_excursion / 2.0);**** > > double ECr = CLAMP( (double)*V, chroma_offset - chroma_excursion / 2.0, > chroma_offset + chroma_excursion / 2.0);**** > > uint8_t r = CLAMP(EY + 2*(1-wr)*ECr, 0, 255);**** > > uint8_t g = CLAMP(EY - ((2*wr*(1-wr) * ECr)/wg) - ((2*wb*(1-wb)*ECb)/wg), > 0 ,255);**** > > uint8_t b = CLAMP(EY + 2*(1-wr)*ECb, 0, 255);**** > > ** ** > > ** ** > > On another point David Schleef tried pointing me to some dirac test > streams, which don’t seem to work with my decoder. When decoding is > attempted they return the error state SCHRO_DECODER_ERROR. **** > > The test streams seem to have been encoded with Schroedinger 1.0.9 whilst I > am using version 1.0.10. Is the error state expected in this case?**** > > ** ** > > Although it looks like garbage I believe it is decoding the video correctly > to a degree as the output image seems to alter in the same way as the vlc > output.**** > > The purplish lines scatter down screen at the same speed as the stars > cascade in the vlc output and it plays for the same length of time.**** > > ** ** > > Any help or guidance as always greatly appreciated.**** > > ** ** > > MarkH. **** > > ** ** > > ** ** > > ** ** > > *From:* Hinchcliffe.Mark > *Sent:* 04 August 2011 10:39 > *To:* 'schrodinger-devel@lists.sourceforge.net' > *Subject:* Schroedinger decoding**** > > ** ** > > Hello all,**** > > ** ** > > I have been trying to write a decoder using libschroedinger for the last > couple of days. I used ffmpeg to generate a schroedinger encoded ogg video > file with no audio using an uncompressed avi video as input. My decoder > parses the ogg file pulling out an ogg_packet then decodes it, which all > appears to work fine.**** > > ** ** > > My first question is ffmpeg encoding using libschroedinger seems to force > the output to use the YUV420 colour space even when specifically requesting > other pixel formats using the ffmpeg –pix_fmt option. Looking at the > schro_frame.h file there appears to be indirect support for > SCHRO_FRAME_FORMAT_ARGB > which would be the ideal format for my purposes; would you be able to > explain what indirect support actually implies here? It also appears > schroedinger only caters for three components (read: colour channels) so how > is Alpha supported in schroedinger / dirac? i.e. will I need to add the > alpha support into schroedinger myself or like other non-alpha codecs would > I have to encode the alpha in the luma component of a grayscale frame?**** > > ** ** > > Finally when storing my frame data in the SCHRO_DECODER_OK state I find the > Schro_Frame occasionally contains NULL data. Meaning my conversion from > YUV420 colour space to RGB cannot proceed for this frame. Is a null frame > expected in this way?**** > > ** ** > > If anyone can provide a link to a dummy video file with expected > schroedinger state transitions that would be fantastic as I could prove my > decoder code against known working decoders.**** > > ** ** > > Thanks for any and all help you can provide.**** > > ** ** > > MarkH.**** > > > ------------------------------------------------------------------------------ > uberSVN's rich system and user administration capabilities and model > configuration take the hassle out of deploying and managing Subversion and > the tools developers use with it. Learn more about uberSVN and get a free > download at: http://p.sf.net/sfu/wandisco-dev2dev > > _______________________________________________ > Schrodinger-devel mailing list > Schrodinger-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/schrodinger-devel > >
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