avutil/pixdesc: deprecate AV_PIX_FMT_FLAG_PSEUDOPAL

PSEUDOPAL pixel formats are not paletted, but carried a palette with the
intention of allowing code to treat unpaletted formats as paletted. The
palette simply mapped the byte values to the resulting RGB values,
making it some sort of LUT for RGB conversion.

It was used for 1 byte formats only: RGB4_BYTE, BGR4_BYTE, RGB8, BGR8,
GRAY8. The first 4 are awfully obscure, used only by some ancient bitmap
formats. The last one, GRAY8, is more common, but its treatment is
grossly incorrect. It considers full range GRAY8 only, so GRAY8 coming
from typical Y video planes was not mapped to the correct RGB values.
This cannot be fixed, because AVFrame.color_range can be freely changed
at runtime, and there is nothing to ensure the pseudo palette is
updated.

Also, nothing actually used the PSEUDOPAL palette data, except xwdenc
(trivially changed in the previous commit). All other code had to treat
it as a special case, just to ignore or to propagate palette data.

In conclusion, this was just a very strange old mechnaism that has no
real justification to exist anymore (although it may have been nice and
useful in the past). Now it's an artifact that makes the API harder to
use: API users who allocate their own pixel data have to be aware that
they need to allocate the palette, or FFmpeg will crash on them in
_some_ situations. On top of this, there was no API to allocate the
pseuo palette outside of av_frame_get_buffer().

This patch not only deprecates AV_PIX_FMT_FLAG_PSEUDOPAL, but also makes
the pseudo palette optional. Nothing accesses it anymore, though if it's
set, it's propagated. It's still allocated and initialized for
compatibility with API users that rely on this feature. But new API
users do not need to allocate it. This was an explicit goal of this
patch.

Most changes replace AV_PIX_FMT_FLAG_PSEUDOPAL with FF_PSEUDOPAL. I
first tried #ifdefing all code, but it was a mess. The FF_PSEUDOPAL
macro reduces the mess, and still allows defining FF_API_PSEUDOPAL to 0.

Passes FATE with FF_API_PSEUDOPAL enabled and disabled. In addition,
FATE passes with FF_API_PSEUDOPAL set to 1, but with allocation
functions manually changed to not allocating a palette.

doc/APIchanges

@@ -15,6 +15,10 @@ libavutil:     2017-10-21
 
 API changes, most recent first:
 
+2018-04-03 - xxxxxxx - lavu 56.13.100 - pixdesc.h
+  Deprecate AV_PIX_FMT_FLAG_PSEUDOPAL and make allocating a pseudo palette
+  optional for API users (see AV_PIX_FMT_FLAG_PSEUDOPAL doxygen for details).
+
 2018-04-01 - xxxxxxx - lavc 58.17.100 - avcodec.h
   Add av_packet_make_refcounted().
 

fftools/ffprobe.c

@@ -3118,7 +3118,9 @@ static void ffprobe_show_pixel_formats(WriterContext *w)
             PRINT_PIX_FMT_FLAG(HWACCEL,   "hwaccel");
             PRINT_PIX_FMT_FLAG(PLANAR,    "planar");
             PRINT_PIX_FMT_FLAG(RGB,       "rgb");
+#if FF_API_PSEUDOPAL
             PRINT_PIX_FMT_FLAG(PSEUDOPAL, "pseudopal");
+#endif
             PRINT_PIX_FMT_FLAG(ALPHA,     "alpha");
             writer_print_section_footer(w);
         }

libavcodec/decode.c

@@ -1614,7 +1614,7 @@ static int video_get_buffer(AVCodecContext *s, AVFrame *pic)
         pic->linesize[i] = 0;
     }
     if (desc->flags & AV_PIX_FMT_FLAG_PAL ||
-        desc->flags & AV_PIX_FMT_FLAG_PSEUDOPAL)
+        ((desc->flags & FF_PSEUDOPAL) && pic->data[1]))
         avpriv_set_systematic_pal2((uint32_t *)pic->data[1], pic->format);
 
     if (s->debug & FF_DEBUG_BUFFERS)
@@ -1782,9 +1782,6 @@ static void validate_avframe_allocation(AVCodecContext *avctx, AVFrame *frame)
         for (i = 0; i < num_planes; i++) {
             av_assert0(frame->data[i]);
         }
-        // For now do not enforce anything for palette of pseudopal formats
-        if (num_planes == 1 && (flags & AV_PIX_FMT_FLAG_PSEUDOPAL))
-            num_planes = 2;
         // For formats without data like hwaccel allow unused pointers to be non-NULL.
         for (i = num_planes; num_planes > 0 && i < FF_ARRAY_ELEMS(frame->data); i++) {
             if (frame->data[i])

libavcodec/ffv1dec.c

@@ -950,7 +950,7 @@ static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame, AVPac
 
             }
             if (desc->flags & AV_PIX_FMT_FLAG_PAL ||
-                desc->flags & AV_PIX_FMT_FLAG_PSEUDOPAL) {
+                desc->flags & FF_PSEUDOPAL) {
                 dst[1] = p->data[1];
                 src[1] = f->last_picture.f->data[1];
             }

libavcodec/rawdec.c

@@ -92,12 +92,14 @@ static av_cold int raw_init_decoder(AVCodecContext *avctx)
         return AVERROR(EINVAL);
     }
 
-    if (desc->flags & (AV_PIX_FMT_FLAG_PAL | AV_PIX_FMT_FLAG_PSEUDOPAL)) {
+    if (desc->flags & (AV_PIX_FMT_FLAG_PAL | FF_PSEUDOPAL)) {
         context->palette = av_buffer_alloc(AVPALETTE_SIZE);
         if (!context->palette)
             return AVERROR(ENOMEM);
+#if FF_API_PSEUDOPAL
         if (desc->flags & AV_PIX_FMT_FLAG_PSEUDOPAL)
             avpriv_set_systematic_pal2((uint32_t*)context->palette->data, avctx->pix_fmt);
+#endif
         else {
             memset(context->palette->data, 0, AVPALETTE_SIZE);
             if (avctx->bits_per_coded_sample == 1)
@@ -423,7 +425,7 @@ static int raw_decode(AVCodecContext *avctx, void *data, int *got_frame,
     }
 
     if ((avctx->pix_fmt == AV_PIX_FMT_PAL8 && buf_size < context->frame_size) ||
-        (desc->flags & AV_PIX_FMT_FLAG_PSEUDOPAL)) {
+        (desc->flags & FF_PSEUDOPAL)) {
         frame->buf[1]  = av_buffer_ref(context->palette);
         if (!frame->buf[1]) {
             av_buffer_unref(&frame->buf[0]);

libavcodec/smvjpegdec.c

@@ -71,7 +71,7 @@ static inline void smv_img_pnt(uint8_t *dst_data[4], uint8_t *src_data[4],
             src_linesizes[i], h, nlines);
     }
     if (desc->flags & AV_PIX_FMT_FLAG_PAL ||
-        desc->flags & AV_PIX_FMT_FLAG_PSEUDOPAL)
+        desc->flags & FF_PSEUDOPAL)
         dst_data[1] = src_data[1];
 }
 

libavfilter/drawutils.c

@@ -184,7 +184,7 @@ int ff_draw_init(FFDrawContext *draw, enum AVPixelFormat format, unsigned flags)
 
     if (!desc || !desc->name)
         return AVERROR(EINVAL);
-    if (desc->flags & ~(AV_PIX_FMT_FLAG_PLANAR | AV_PIX_FMT_FLAG_RGB | AV_PIX_FMT_FLAG_PSEUDOPAL | AV_PIX_FMT_FLAG_ALPHA))
+    if (desc->flags & ~(AV_PIX_FMT_FLAG_PLANAR | AV_PIX_FMT_FLAG_RGB | FF_PSEUDOPAL | AV_PIX_FMT_FLAG_ALPHA))
         return AVERROR(ENOSYS);
     if (format == AV_PIX_FMT_P010LE || format == AV_PIX_FMT_P010BE || format == AV_PIX_FMT_P016LE || format == AV_PIX_FMT_P016BE)
         return AVERROR(ENOSYS);

libavfilter/framepool.c

@@ -103,7 +103,7 @@ FFFramePool *ff_frame_pool_video_init(AVBufferRef* (*alloc)(int size),
     }
 
     if (desc->flags & AV_PIX_FMT_FLAG_PAL ||
-        desc->flags & AV_PIX_FMT_FLAG_PSEUDOPAL) {
+        desc->flags & FF_PSEUDOPAL) {
         pool->pools[1] = av_buffer_pool_init(AVPALETTE_SIZE, alloc);
         if (!pool->pools[1])
             goto fail;
@@ -227,7 +227,7 @@ AVFrame *ff_frame_pool_get(FFFramePool *pool)
         }
 
         if (desc->flags & AV_PIX_FMT_FLAG_PAL ||
-            desc->flags & AV_PIX_FMT_FLAG_PSEUDOPAL) {
+            desc->flags & FF_PSEUDOPAL) {
             enum AVPixelFormat format =
                 pool->format == AV_PIX_FMT_PAL8 ? AV_PIX_FMT_BGR8 : pool->format;
 

libavfilter/vf_crop.c

@@ -288,7 +288,7 @@ static int filter_frame(AVFilterLink *link, AVFrame *frame)
     frame->data[0] += s->y * frame->linesize[0];
     frame->data[0] += s->x * s->max_step[0];
 
-    if (!(desc->flags & AV_PIX_FMT_FLAG_PAL || desc->flags & AV_PIX_FMT_FLAG_PSEUDOPAL)) {
+    if (!(desc->flags & AV_PIX_FMT_FLAG_PAL || desc->flags & FF_PSEUDOPAL)) {
         for (i = 1; i < 3; i ++) {
             if (frame->data[i]) {
                 frame->data[i] += (s->y >> s->vsub) * frame->linesize[i];

libavfilter/vf_pixdesctest.c

@@ -81,7 +81,7 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *in)
 
     /* copy palette */
     if (priv->pix_desc->flags & AV_PIX_FMT_FLAG_PAL ||
-        priv->pix_desc->flags & AV_PIX_FMT_FLAG_PSEUDOPAL)
+        ((priv->pix_desc->flags & FF_PSEUDOPAL) && out->data[1] && in->data[1]))
         memcpy(out->data[1], in->data[1], AVPALETTE_SIZE);
 
     for (c = 0; c < priv->pix_desc->nb_components; c++) {

libavfilter/vf_scale.c

@@ -261,11 +261,10 @@ static int config_props(AVFilterLink *outlink)
 
     /* TODO: make algorithm configurable */
 
-    scale->input_is_pal = desc->flags & AV_PIX_FMT_FLAG_PAL ||
-                          desc->flags & AV_PIX_FMT_FLAG_PSEUDOPAL;
+    scale->input_is_pal = desc->flags & AV_PIX_FMT_FLAG_PAL;
     if (outfmt == AV_PIX_FMT_PAL8) outfmt = AV_PIX_FMT_BGR8;
     scale->output_is_pal = av_pix_fmt_desc_get(outfmt)->flags & AV_PIX_FMT_FLAG_PAL ||
-                           av_pix_fmt_desc_get(outfmt)->flags & AV_PIX_FMT_FLAG_PSEUDOPAL;
+                           av_pix_fmt_desc_get(outfmt)->flags & FF_PSEUDOPAL;
 
     if (scale->sws)
         sws_freeContext(scale->sws);

libavfilter/vf_shuffleplanes.c

@@ -69,7 +69,7 @@ static av_cold int shuffleplanes_config_input(AVFilterLink *inlink)
         }
 
         if ((desc->flags & AV_PIX_FMT_FLAG_PAL ||
-             desc->flags & AV_PIX_FMT_FLAG_PSEUDOPAL) &&
+             desc->flags & FF_PSEUDOPAL) &&
             (i == 1) != (s->map[i] == 1)) {
             av_log(ctx, AV_LOG_ERROR,
                    "Cannot map between a palette plane and a data plane.\n");

libavutil/frame.c

@@ -247,7 +247,7 @@ static int get_video_buffer(AVFrame *frame, int align)
 
         frame->data[i] = frame->buf[i]->data;
     }
-    if (desc->flags & AV_PIX_FMT_FLAG_PAL || desc->flags & AV_PIX_FMT_FLAG_PSEUDOPAL) {
+    if (desc->flags & AV_PIX_FMT_FLAG_PAL || desc->flags & FF_PSEUDOPAL) {
         av_buffer_unref(&frame->buf[1]);
         frame->buf[1] = av_buffer_alloc(AVPALETTE_SIZE);
         if (!frame->buf[1])
@@ -848,7 +848,7 @@ static int calc_cropping_offsets(size_t offsets[4], const AVFrame *frame,
         int shift_x = (i == 1 || i == 2) ? desc->log2_chroma_w : 0;
         int shift_y = (i == 1 || i == 2) ? desc->log2_chroma_h : 0;
 
-        if (desc->flags & (AV_PIX_FMT_FLAG_PAL | AV_PIX_FMT_FLAG_PSEUDOPAL) && i == 1) {
+        if (desc->flags & (AV_PIX_FMT_FLAG_PAL | FF_PSEUDOPAL) && i == 1) {
             offsets[i] = 0;
             break;
         }

libavutil/imgutils.c

@@ -125,7 +125,7 @@ int av_image_fill_pointers(uint8_t *data[4], enum AVPixelFormat pix_fmt, int hei
     size[0] = linesizes[0] * height;
 
     if (desc->flags & AV_PIX_FMT_FLAG_PAL ||
-        desc->flags & AV_PIX_FMT_FLAG_PSEUDOPAL) {
+        desc->flags & FF_PSEUDOPAL) {
         data[1] = ptr + size[0]; /* palette is stored here as 256 32 bits words */
         return size[0] + 256 * 4;
     }
@@ -216,7 +216,7 @@ int av_image_alloc(uint8_t *pointers[4], int linesizes[4],
         av_free(buf);
         return ret;
     }
-    if (desc->flags & AV_PIX_FMT_FLAG_PAL || desc->flags & AV_PIX_FMT_FLAG_PSEUDOPAL) {
+    if (desc->flags & AV_PIX_FMT_FLAG_PAL || (desc->flags & FF_PSEUDOPAL && pointers[1])) {
         avpriv_set_systematic_pal2((uint32_t*)pointers[1], pix_fmt);
         if (align < 4) {
             av_log(NULL, AV_LOG_ERROR, "Formats with a palette require a minimum alignment of 4\n");
@@ -225,7 +225,7 @@ int av_image_alloc(uint8_t *pointers[4], int linesizes[4],
     }
 
     if ((desc->flags & AV_PIX_FMT_FLAG_PAL ||
-         desc->flags & AV_PIX_FMT_FLAG_PSEUDOPAL) &&
+         desc->flags & FF_PSEUDOPAL) && pointers[1] &&
         pointers[1] - pointers[0] > linesizes[0] * h) {
         /* zero-initialize the padding before the palette */
         memset(pointers[0] + linesizes[0] * h, 0,
@@ -354,12 +354,13 @@ static void image_copy(uint8_t *dst_data[4], const ptrdiff_t dst_linesizes[4],
         return;
 
     if (desc->flags & AV_PIX_FMT_FLAG_PAL ||
-        desc->flags & AV_PIX_FMT_FLAG_PSEUDOPAL) {
+        desc->flags & FF_PSEUDOPAL) {
         copy_plane(dst_data[0], dst_linesizes[0],
                    src_data[0], src_linesizes[0],
                    width, height);
         /* copy the palette */
-        memcpy(dst_data[1], src_data[1], 4*256);
+        if ((desc->flags & AV_PIX_FMT_FLAG_PAL) || (dst_data[1] && src_data[1]))
+            memcpy(dst_data[1], src_data[1], 4*256);
     } else {
         int i, planes_nb = 0;
 
@@ -442,7 +443,7 @@ int av_image_get_buffer_size(enum AVPixelFormat pix_fmt,
         return ret;
 
     // do not include palette for these pseudo-paletted formats
-    if (desc->flags & AV_PIX_FMT_FLAG_PSEUDOPAL)
+    if (desc->flags & FF_PSEUDOPAL)
         return FFALIGN(width, align) * height;
 
     return av_image_fill_arrays(data, linesize, NULL, pix_fmt,

libavutil/internal.h

@@ -360,4 +360,13 @@ void ff_check_pixfmt_descriptors(void);
  */
 int avpriv_dict_set_timestamp(AVDictionary **dict, const char *key, int64_t timestamp);
 
+// Helper macro for AV_PIX_FMT_FLAG_PSEUDOPAL deprecation. Code inside FFmpeg
+// should always use FF_PSEUDOPAL. Once the public API flag gets removed, all
+// code using it is dead code.
+#if FF_API_PSEUDOPAL
+#define FF_PSEUDOPAL AV_PIX_FMT_FLAG_PSEUDOPAL
+#else
+#define FF_PSEUDOPAL 0
+#endif
+
 #endif /* AVUTIL_INTERNAL_H */

libavutil/pixdesc.c

@@ -257,7 +257,7 @@ static const AVPixFmtDescriptor av_pix_fmt_descriptors[AV_PIX_FMT_NB] = {
         .comp = {
             { 0, 1, 0, 0, 8, 0, 7, 1 },        /* Y */
         },
-        .flags = AV_PIX_FMT_FLAG_PSEUDOPAL,
+        .flags = FF_PSEUDOPAL,
         .alias = "gray8,y8",
     },
     [AV_PIX_FMT_MONOWHITE] = {
@@ -362,7 +362,7 @@ static const AVPixFmtDescriptor av_pix_fmt_descriptors[AV_PIX_FMT_NB] = {
             { 0, 1, 0, 3, 3, 0, 2, 1 },        /* G */
             { 0, 1, 0, 6, 2, 0, 1, 1 },        /* B */
         },
-        .flags = AV_PIX_FMT_FLAG_RGB | AV_PIX_FMT_FLAG_PSEUDOPAL,
+        .flags = AV_PIX_FMT_FLAG_RGB | FF_PSEUDOPAL,
     },
     [AV_PIX_FMT_BGR4] = {
         .name = "bgr4",
@@ -386,7 +386,7 @@ static const AVPixFmtDescriptor av_pix_fmt_descriptors[AV_PIX_FMT_NB] = {
             { 0, 1, 0, 1, 2, 0, 1, 1 },        /* G */
             { 0, 1, 0, 3, 1, 0, 0, 1 },        /* B */
         },
-        .flags = AV_PIX_FMT_FLAG_RGB | AV_PIX_FMT_FLAG_PSEUDOPAL,
+        .flags = AV_PIX_FMT_FLAG_RGB | FF_PSEUDOPAL,
     },
     [AV_PIX_FMT_RGB8] = {
         .name = "rgb8",
@@ -398,7 +398,7 @@ static const AVPixFmtDescriptor av_pix_fmt_descriptors[AV_PIX_FMT_NB] = {
             { 0, 1, 0, 3, 3, 0, 2, 1 },        /* G */
             { 0, 1, 0, 0, 3, 0, 2, 1 },        /* B */
         },
-        .flags = AV_PIX_FMT_FLAG_RGB | AV_PIX_FMT_FLAG_PSEUDOPAL,
+        .flags = AV_PIX_FMT_FLAG_RGB | FF_PSEUDOPAL,
     },
     [AV_PIX_FMT_RGB4] = {
         .name = "rgb4",
@@ -422,7 +422,7 @@ static const AVPixFmtDescriptor av_pix_fmt_descriptors[AV_PIX_FMT_NB] = {
             { 0, 1, 0, 1, 2, 0, 1, 1 },        /* G */
             { 0, 1, 0, 0, 1, 0, 0, 1 },        /* B */
         },
-        .flags = AV_PIX_FMT_FLAG_RGB | AV_PIX_FMT_FLAG_PSEUDOPAL,
+        .flags = AV_PIX_FMT_FLAG_RGB | FF_PSEUDOPAL,
     },
     [AV_PIX_FMT_NV12] = {
         .name = "nv12",

libavutil/pixdesc.h

@@ -154,6 +154,14 @@ typedef struct AVPixFmtDescriptor {
  * in some cases be simpler. Or the data can be interpreted purely based on
  * the pixel format without using the palette.
  * An example of a pseudo-paletted format is AV_PIX_FMT_GRAY8
+ *
+ * @deprecated This flag is deprecated, and will be removed. When it is removed,
+ * the extra palette allocation in AVFrame.data[1] is removed as well. Only
+ * actual paletted formats (as indicated by AV_PIX_FMT_FLAG_PAL) will have a
+ * palette. Starting with FFmpeg versions which have this flag deprecated, the
+ * extra "pseudo" palette is already ignored, and API users are not required to
+ * allocate a palette for AV_PIX_FMT_FLAG_PSEUDOPAL formats (it was required
+ * before the deprecation, though).
  */
 #define AV_PIX_FMT_FLAG_PSEUDOPAL    (1 << 6)
 

libavutil/version.h

@@ -79,7 +79,7 @@
  */
 
 #define LIBAVUTIL_VERSION_MAJOR  56
-#define LIBAVUTIL_VERSION_MINOR  12
+#define LIBAVUTIL_VERSION_MINOR  13
 #define LIBAVUTIL_VERSION_MICRO 100
 
 #define LIBAVUTIL_VERSION_INT   AV_VERSION_INT(LIBAVUTIL_VERSION_MAJOR, \
@@ -126,6 +126,9 @@
 #ifndef FF_API_FRAME_GET_SET
 #define FF_API_FRAME_GET_SET            (LIBAVUTIL_VERSION_MAJOR < 57)
 #endif
+#ifndef FF_API_PSEUDOPAL
+#define FF_API_PSEUDOPAL                (LIBAVUTIL_VERSION_MAJOR < 57)
+#endif
 
 
 /**

libswscale/swscale_internal.h

@@ -806,9 +806,17 @@ static av_always_inline int isPlanarRGB(enum AVPixelFormat pix_fmt)
 
 static av_always_inline int usePal(enum AVPixelFormat pix_fmt)
 {
-    const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(pix_fmt);
-    av_assert0(desc);
-    return (desc->flags & AV_PIX_FMT_FLAG_PAL) || (desc->flags & AV_PIX_FMT_FLAG_PSEUDOPAL);
+    switch (pix_fmt) {
+    case AV_PIX_FMT_PAL8:
+    case AV_PIX_FMT_BGR4_BYTE:
+    case AV_PIX_FMT_BGR8:
+    case AV_PIX_FMT_GRAY8:
+    case AV_PIX_FMT_RGB4_BYTE:
+    case AV_PIX_FMT_RGB8:
+        return 1;
+    default:
+        return 0;
+    }
 }
 
 extern const uint64_t ff_dither4[2];