[FFmpeg-devel] [PATCH 1/3] mjpegenc_common: check for codec ID before using avctx->priv_data

[Rostislav Pehlivanov]

On 5 April 2017 at 20:20, Michael Niedermayer <michael at niedermayer.cc>
wrote:

> On Mon, Apr 03, 2017 at 09:13:28PM +0100, Rostislav Pehlivanov wrote:
> > When coding lossless jpeg the priv context will be pointing to
> LJpegEncContext
> > rather than MpegEncContext, which the function expects.
> >
> > Signed-off-by: Rostislav Pehlivanov <atomnuker at gmail.com>
> > ---
> >  libavcodec/mjpegenc_common.c | 10 +++++++---
> >  1 file changed, 7 insertions(+), 3 deletions(-)
> >
> > diff --git a/libavcodec/mjpegenc_common.c b/libavcodec/mjpegenc_common.c
> > index 83a9e95766..6d9c982726 100644
> > --- a/libavcodec/mjpegenc_common.c
> > +++ b/libavcodec/mjpegenc_common.c
> > @@ -91,13 +91,17 @@ static void jpeg_table_header(AVCodecContext
> *avctx, PutBitContext *p,
> >  {
> >      int i, j, size;
> >      uint8_t *ptr;
> > -    MpegEncContext *s = avctx->priv_data;
> > +    MpegEncContext *s = NULL;
> > +
> > +    /* Since avctx->priv_data will point to LJpegEncContext in this
> case */
> > +    if (avctx->codec_id != AV_CODEC_ID_LJPEG)
> > +        s = avctx->priv_data;
> >
> >      if (avctx->codec_id != AV_CODEC_ID_LJPEG) {
> >          int matrix_count = 1 + !!memcmp(luma_intra_matrix,
> >                                          chroma_intra_matrix,
> >                                          sizeof(luma_intra_matrix[0]) *
> 64);
> > -    if (s->force_duplicated_matrix)
> > +    if (s && s->force_duplicated_matrix)
> >          matrix_count = 2;
> >      /* quant matrixes */
> >      put_marker(p, DQT);
>
> > @@ -134,7 +138,7 @@ static void jpeg_table_header(AVCodecContext
> *avctx, PutBitContext *p,
> >
> >      // Only MJPEG can have a variable Huffman variable. All other
> >      // formats use the default Huffman table.
> > -    if (s->out_format == FMT_MJPEG && s->huffman ==
> HUFFMAN_TABLE_OPTIMAL) {
> > +    if (s && s->huffman == HUFFMAN_TABLE_OPTIMAL) {
> >          size += put_huffman_table(p, 0, 0, s->mjpeg_ctx->bits_dc_
> luminance,
> >                                    s->mjpeg_ctx->val_dc_luminance);
> >          size += put_huffman_table(p, 0, 1, s->mjpeg_ctx->bits_dc_
> chrominance,
>
> ljpeg uses the same huffman tables as mjpeg,the same
> ff_mjpeg_encode_dc()
>
> instead of special casing ljpeg it would be better if the identical
> huffman stuff would be shared and the same
>
> [...]
> --
> Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
>
> Republics decline into democracies and democracies degenerate into
> despotisms. -- Aristotle
>
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>
>
Pushed to master and release/3.3 as-is for now. I'll send a separate patch
to fix and enable optimized huffman in ljpeg later.