[FFmpeg-devel] [PATCH] avformat/avidec: ensure that palette does not contain the BottomUp info.

[Michael Niedermayer]

On Tue, Sep 23, 2014 at 01:33:30PM +0200, Benoit Fouet wrote:
> Hi,
> 
> ----- Mail original -----
> > Hi,
> > 
> > ----- Mail original -----
> > > On Tue, Sep 23, 2014 at 10:19:17AM +0200, Benoit Fouet wrote:
> > 
> > > > Here is a patch to illustrate this...
> > > 
> > > this looks better but:
> > > 
> > > 
> > > [...]
> > > > -                ff_put_bmp_header(pb, enc, ff_codec_bmp_tags, 0,
> > > > 0);
> > > > +                if (keep_height) {
> > > > +                    enc->extradata_size -= 9;
> > > > +                    if (!enc->extradata_size)
> > > > +                        av_freep(&enc->extradata);
> > > > +                }
> > > 
> > > what if extradata is stored in 2 files, the 2nd muxer would no
> > > longer
> > > see it
> > > also the muxer shouldnt change the encoders/demuxer extradata
> > > 
> > > and cant all this logic be put in ff_put_bmp_header() ?
> > > might even be simpler
> > > 
> > 
> > Do you mean that ff_put_bmp_header() would check for the BottomUp
> > presence and not negate height in this case, and also only write the
> > palette in the stream?
> > 
> 
> Patch attached, just in case this is what you meant...

>  riffenc.c |    6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> d3a93efc5680ad2340086a61ba3d59749f67e770  0001-avformat-riffenc-extend-ff_put_bmp_header-to-be-able.patch
> From b8c8f07555769215af7a10c48e7a479f783a7c49 Mon Sep 17 00:00:00 2001
> From: Benoit Fouet <benoit.fouet at free.fr>
> Date: Tue, 23 Sep 2014 10:07:10 +0200
> Subject: [PATCH] avformat/riffenc: extend ff_put_bmp_header to be able to
>  force height to not be changed.
> 
> When stream copying, height shouldn't be changed when writing the
> BITMAPINFOHEADER header if the BottomUp information is present in the
> extradata.
> ---
>  libavformat/riffenc.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/libavformat/riffenc.c b/libavformat/riffenc.c
> index ef4d399..f1a2274 100644
> --- a/libavformat/riffenc.c
> +++ b/libavformat/riffenc.c
> @@ -209,11 +209,13 @@ int ff_put_wav_header(AVIOContext *pb, AVCodecContext *enc, int flags)
>  void ff_put_bmp_header(AVIOContext *pb, AVCodecContext *enc,
>                         const AVCodecTag *tags, int for_asf, int ignore_extradata)
>  {
> +    int keep_height = enc->extradata_size >= 9 &&
> +                      !memcmp(enc->extradata + enc->extradata_size - 9, "BottomUp", 9);
>      /* size */
>      avio_wl32(pb, 40 + (ignore_extradata ? 0 : enc->extradata_size));
>      avio_wl32(pb, enc->width);
>      //We always store RGB TopDown
> -    avio_wl32(pb, enc->codec_tag ? enc->height : -enc->height);
> +    avio_wl32(pb, enc->codec_tag || keep_height ? enc->height : -enc->height);
>      /* planes */
>      avio_wl16(pb, 1);
>      /* depth */

> @@ -227,7 +229,7 @@ void ff_put_bmp_header(AVIOContext *pb, AVCodecContext *enc,
>      avio_wl32(pb, 0);
>  
>      if (!ignore_extradata) {
> -        avio_write(pb, enc->extradata, enc->extradata_size);
> +        avio_write(pb, enc->extradata, keep_height ? enc->extradata_size : enc->extradata_size - 9);

this corrupts the stored extradata and breaks fate

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

If a bugfix only changes things apparently unrelated to the bug with no
further explanation, that is a good sign that the bugfix is wrong.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 181 bytes
Desc: Digital signature
URL: <https://ffmpeg.org/pipermail/ffmpeg-devel/attachments/20140923/6190dde4/attachment.asc>