[FFmpeg-devel] [PATCH v9] lavf: palettized QuickTime video in Matroska

Michael Niedermayer michael at niedermayer.cc
Mon Dec 28 15:29:45 CET 2015


On Mon, Dec 28, 2015 at 12:07:38PM +0100, Nicolas George wrote:
> L'octidi 8 nivôse, an CCXXIV, Mats Peterson a écrit :
> > Michael, he's talking about the OLD patch that was never applied. My patch
> > has been written from scratch, more or less. I did borrowed some palette
> > loops from mov.c, but I have also attributed the previous authors at the top
> > of qtpalette.c properly.
> 
> I must say, I find this hunk from 7973603:
> 
> +        if (matroska->has_palette) {
> +            uint8_t *pal = av_packet_new_side_data(pkt, AV_PKT_DATA_PALETTE, AVPALETTE_SIZE);
> +            if (!pal) {
> +                av_log(matroska->ctx, AV_LOG_ERROR, "Cannot append palette to packet\n");
> +            } else {
> +                memcpy(pal, matroska->palette, AVPALETTE_SIZE);
> +            }
> +            matroska->has_palette = 0;
> +        }
> 
> looks quite similar to this hunk from
> https://trac.ffmpeg.org/attachment/ticket/5071/patchmkvmov.diff :
> 
> +        if (matroska->pal) {
> +            uint8_t *pal = av_packet_new_side_data(pkt, AV_PKT_DATA_PALETTE, AVPALETTE_SIZE);
> +            if (!pal) {
> +                av_log(matroska->ctx, AV_LOG_ERROR, "Cannot append palette to packet\n");
> +            } else {
> +                memcpy(pal, matroska->pal, AVPALETTE_SIZE);
> +            }
> +            av_freep(&matroska->pal);
> +        }
> 
> Especially the use of if/else for error, and actually ignoring the error,
> instead of the most common (and more correct, but the rest of the code
> ignores error too) "if...return AVERROR(ENOMEM)".

for reference: (similar code prior to the patches)

HEAD~20:libavdevice/x11grab.c-    pkt->pts  = curtime;
HEAD~20:libavdevice/x11grab.c-    if (s->palette_changed) {
HEAD~20:libavdevice/x11grab.c-        uint8_t *pal = av_packet_new_side_data(pkt, AV_PKT_DATA_PALETTE,
HEAD~20:libavdevice/x11grab.c-                                               AVPALETTE_SIZE);
HEAD~20:libavdevice/x11grab.c-        if (!pal) {
HEAD~20:libavdevice/x11grab.c:            av_log(s, AV_LOG_ERROR, "Cannot append palette to packet\n");
HEAD~20:libavdevice/x11grab.c-        } else {
HEAD~20:libavdevice/x11grab.c-            memcpy(pal, s->palette, AVPALETTE_SIZE);
HEAD~20:libavdevice/x11grab.c-            s->palette_changed = 0;
HEAD~20:libavdevice/x11grab.c-        }
HEAD~20:libavdevice/x11grab.c-    }
--
HEAD~20:libavformat/asfdec_f.c-            if (asf_st->pkt.data && asf_st->palette_changed) {
HEAD~20:libavformat/asfdec_f.c-                uint8_t *pal;
HEAD~20:libavformat/asfdec_f.c-                pal = av_packet_new_side_data(&asf_st->pkt, AV_PKT_DATA_PALETTE,
HEAD~20:libavformat/asfdec_f.c-                                              AVPALETTE_SIZE);
HEAD~20:libavformat/asfdec_f.c-                if (!pal) {
HEAD~20:libavformat/asfdec_f.c:                    av_log(s, AV_LOG_ERROR, "Cannot append palette to packet\n");
HEAD~20:libavformat/asfdec_f.c-                } else {
HEAD~20:libavformat/asfdec_f.c-                    memcpy(pal, asf_st->palette, AVPALETTE_SIZE);
HEAD~20:libavformat/asfdec_f.c-                    asf_st->palette_changed = 0;
HEAD~20:libavformat/asfdec_f.c-                }
HEAD~20:libavformat/asfdec_f.c-            }
--
HEAD~20:libavformat/mov.c-        if (sc->has_palette) {
HEAD~20:libavformat/mov.c-            uint8_t *pal;
HEAD~20:libavformat/mov.c-
HEAD~20:libavformat/mov.c-            pal = av_packet_new_side_data(pkt, AV_PKT_DATA_PALETTE, AVPALETTE_SIZE);
HEAD~20:libavformat/mov.c-            if (!pal) {
HEAD~20:libavformat/mov.c:                av_log(mov->fc, AV_LOG_ERROR, "Cannot append palette to packet\n");
HEAD~20:libavformat/mov.c-            } else {
HEAD~20:libavformat/mov.c-                memcpy(pal, sc->palette, AVPALETTE_SIZE);
HEAD~20:libavformat/mov.c-                sc->has_palette = 0;
HEAD~20:libavformat/mov.c-            }
HEAD~20:libavformat/mov.c-        }

[...]

-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Dictatorship naturally arises out of democracy, and the most aggravated
form of tyranny and slavery out of the most extreme liberty. -- Plato
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 181 bytes
Desc: Digital signature
URL: <http://ffmpeg.org/pipermail/ffmpeg-devel/attachments/20151228/75921f9e/attachment.sig>


More information about the ffmpeg-devel mailing list