[FFmpeg-devel] Fwd: [PATCH] Psygnosis YOP demuxer

[Michael Niedermayer]

On Thu, Feb 18, 2010 at 05:35:59PM +0530, Mohamed Naufal wrote:
> On 15 January 2010 05:41, Michael Niedermayer <michaelni at gmx.at> wrote:
> 
> 
> [...]
> 
> 
> > > +typedef struct YopDecContext {
> > > +    AVFrame frame;
> > > +    AVCodecContext *avctx;
> > > +    AVPacket *avpkt;
> > > +
> > > +    int num_pal_colors;
> > > +    int first_color[2];
> > > +    int tag_needs_next_byte;
> >
> > > +    int current_tag_byte;
> >
> > you dont need that variable
> >
> 
> If I don't increment s->srcptr in the if block of yop_get_next_nibble(),
> color_num in yop_paint_block() can have an incorrect value.

you dont need the current_tag_byte variable


> 
> [...]
> 
> 

> > > +/**
> > > + * Update the palette based on the frame number. Consume all of the
> > palette
> > > + * bytes on the input.
> > > + */
> > > +static void yop_update_palette(YopDecContext *s)
> > > +{
> > > +    int firstcolor;
> > > +    int i, j;
> > > +
> > > +    firstcolor = s->first_color[s->avctx->frame_number & 1];
> >
> > this will be wrong with seeking id suspect
> >
> 
> 
> How else do I do it?

Either the demuxer marks only even frames as keyframe then the decoder
can when it detects seeking start counting from even
or
the demuxer has to indicate if a frame is even or odd to the decoder
also there is the question if they are keyframes or not, you obviosuly
should not mark then incorrectly

[...]
> +    s->row_pos = 0;
> +
> +    while ((size_t) s->dstptr - (size_t) s->dstbuf <
> +           avctx->width * RGB_COLORS * avctx->height &&
> +           (size_t) s->srcptr - (size_t) avpkt->data < avpkt->size) {
> +        current_nibble = yop_get_next_nibble(s);

useless casts


[...]
> +AVInputFormat yop_demuxer = {
> +    "yop",
> +    NULL_IF_CONFIG_SMALL("Psygnosis YOP Format"),
> +    sizeof(YopDecContext),
> +    yop_probe,
> +    yop_read_header,
> +    yop_read_packet,
> +    yop_read_close,
> +    .extensions = "yop",
> +    .flags = AVFMT_GENERIC_INDEX,
> +};

thats missing code to flush the buffered packet in case of seeking


[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Frequently ignored awnser#1 FFmpeg bugs should be sent to our bugtracker. User
questions about the command line tools should be sent to the ffmpeg-user ML.
And questions about how to use libav* should be sent to the libav-user ML.
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