jpegdec: Support libjpeg-turbo colorspace conversion

The libjpeg-turbo has a built-in support for performing colorspace
conversion. The performance of this conversion is much better than
doing the same separately using videoconvert. Implement support for
this conversion to RGBx/xRGB/BGRx/xBGR formats. Other formats can
be easily added later.

- The decoding of various pixel formats can be tested and compared to
  non-libjpeg-turbo decoding as follows:
  for gfmt in {RGB,BGR}{,x} x{RGB,BGR} ; do
      echo "$gfmt"
      gst-launch-1.0 -q \
          videotestsrc pattern=colors ! \
          video/x-raw,format=${gfmt} ! \
          fakesink dump=true | \
	  head -n 200 | tail -n 1
      gst-launch-1.0 -q --gst-plugin-path=build/ext/jpeg/ \
          videotestsrc pattern=colors ! \
          video/x-raw,format=${gfmt} ! \
	  jpegenc ! \
	  jpegdec ! \
	  video/x-raw,format=${gfmt} ! \
	  fakesink dump=true | \
	  head -n 200 | tail -n 1
      done
  Result looks as follows, i.e. comparable:
  RGB
  00000c70 (0x7f7736fbdd10): 05 33 19 05 33 26 05 33 33 05 33 40 05 33 4c 05  .3..3&.33.3@.3L.
  00000c70 (0x7f389e8f7d10): 05 32 17 04 32 22 04 32 31 04 32 3e 04 32 4a 04  .2..2".21.2>.2J.
  RGBx
  00000c70 (0x7f79efd0ad10): cc 07 22 ff d9 07 22 ff e6 07 22 ff f3 07 22 ff  .."..."..."...".
  00000c70 (0x7fb6989f3d10): cd 06 22 00 d9 06 22 00 e6 06 22 00 f4 06 22 00  .."..."..."...".
  BGR
  00000c70 (0x7fa0a6c42d10): 05 0c 33 05 19 33 05 26 33 05 33 33 05 40 33 05  ..3..3.&3.33.@3.
  00000c70 (0x7fc74165fd10): 05 08 32 04 17 32 04 22 32 04 31 32 04 3e 32 04  ..2..2."2.12.>2.
  BGRx
  00000c70 (0x7fbf399f1d10): 22 07 cc ff 22 07 d9 ff 22 07 e6 ff 22 07 f3 ff  "..."..."..."...
  00000c70 (0x7f50e3d1cd10): 22 06 cd 00 22 06 d9 00 22 06 e6 00 22 06 f4 00  "..."..."..."...
  xRGB
  00000c70 (0x7f0b950a2d10): ff cc 07 22 ff d9 07 22 ff e6 07 22 ff f3 07 22  ..."..."..."..."
  00000c70 (0x7f4416b8dd10): 00 cd 06 22 00 d9 06 22 00 e6 06 22 00 f4 06 22  ..."..."..."..."
  xBGR
  00000c70 (0x7f237d74dd10): ff 22 07 cc ff 22 07 d9 ff 22 07 e6 ff 22 07 f3  ."..."..."..."..
  00000c70 (0x7f095547dd10): 00 22 06 cd 00 22 06 d9 00 22 06 e6 00 22 06 f4  ."..."..."..."..
                             ^^          ^^          ^^          ^^
  Notice how the alpha channel is set to arbitrary value in case of the
  libjpeg-turbo decoding into RGBx/BGRx/xRGB/xBGR pixel formats. This is
  documented in libjpeg-turbo README.md as follows:
    "
    When using the RGBX, BGRX, XBGR, and XRGB colorspaces during decompression, the
    X byte is undefined, and in order to ensure the best performance, libjpeg-turbo
    can set that byte to whatever value it wishes.
    "

- The interlaced num_fields=2 mjpeg stream can be generated and
  tested as follows (this does require mjpegtools):
  $ gst-launch-1.0 videotestsrc num-buffers=10 ! jpegenc ! multifilesink location=in%04d.jpg
  $ jpeg2yuv -f 25 -I t -L 0 -j in%04d.jpg | yuv2lav -f avi -o result.avi
  ...
  $ gst-launch-1.0 --gst-plugin-path=build/ext/jpeg/ filesrc location=result.avi ! \
       avidemux ! jpegdec ! video/x-raw,format=RGBx ! videoconvert ! autovideosink

Signed-off-by: Marek Vasut <marex@denx.de>
Part-of: <https://gitlab.freedesktop.org/gstreamer/gstreamer/-/merge_requests/1091>

subprojects/gst-plugins-good/ext/jpeg/gstjpegdec.c

@@ -913,6 +913,27 @@ gst_jpeg_dec_decode_direct (GstJpegDec * dec, GstVideoFrame * frame,
   /* let jpeglib decode directly into our final buffer */
   GST_DEBUG_OBJECT (dec, "decoding directly into output buffer");
 
+#ifdef JCS_EXTENSIONS
+  if (dec->format_convert) {
+    gint row_stride = dec->cinfo.output_width * dec->cinfo.output_components;
+    guchar *bufbase = GST_VIDEO_FRAME_PLANE_DATA (frame, 0);
+
+    if (num_fields == 2) {
+      row_stride *= 2;
+    }
+
+    if (field == 2) {
+      bufbase += GST_VIDEO_FRAME_PLANE_STRIDE (frame, 0);
+    }
+
+    while (dec->cinfo.output_scanline < dec->cinfo.output_height) {
+      JSAMPARRAY buffer = { &bufbase, };
+      jpeg_read_scanlines (&dec->cinfo, buffer, 1);
+      bufbase += row_stride;
+    }
+  } else
+#endif
+  {
     for (i = 0; i < height; i += v_samp[0] * DCTSIZE) {
       for (j = 0; j < (v_samp[0] * DCTSIZE); ++j) {
         /* Y */
@@ -942,6 +963,7 @@ gst_jpeg_dec_decode_direct (GstJpegDec * dec, GstVideoFrame * frame,
         GST_INFO_OBJECT (dec, "jpeg_read_raw_data() returned 0");
       }
     }
+  }
   return GST_FLOW_OK;
 
 format_not_supported:
@@ -957,6 +979,37 @@ format_not_supported:
   }
 }
 
+#ifdef JCS_EXTENSIONS
+static J_COLOR_SPACE
+gst_fmt_to_jpeg_turbo_ext_fmt (GstVideoFormat gstfmt)
+{
+  switch (gstfmt) {
+    case GST_VIDEO_FORMAT_RGB:
+      return JCS_EXT_RGB;
+    case GST_VIDEO_FORMAT_RGBx:
+      return JCS_EXT_RGBX;
+    case GST_VIDEO_FORMAT_xRGB:
+      return JCS_EXT_XRGB;
+    case GST_VIDEO_FORMAT_RGBA:
+      return JCS_EXT_RGBA;
+    case GST_VIDEO_FORMAT_ARGB:
+      return JCS_EXT_ARGB;
+    case GST_VIDEO_FORMAT_BGR:
+      return JCS_EXT_BGR;
+    case GST_VIDEO_FORMAT_BGRx:
+      return JCS_EXT_BGRX;
+    case GST_VIDEO_FORMAT_xBGR:
+      return JCS_EXT_XBGR;
+    case GST_VIDEO_FORMAT_BGRA:
+      return JCS_EXT_BGRA;
+    case GST_VIDEO_FORMAT_ABGR:
+      return JCS_EXT_ABGR;
+    default:
+      return 0;
+  }
+}
+#endif
+
 static void
 gst_jpeg_dec_negotiate (GstJpegDec * dec, gint width, gint height, gint clrspc,
     gboolean interlaced)
@@ -964,7 +1017,14 @@ gst_jpeg_dec_negotiate (GstJpegDec * dec, gint width, gint height, gint clrspc,
   GstVideoCodecState *outstate;
   GstVideoInfo *info;
   GstVideoFormat format;
+  GstCaps *peer_caps, *dec_caps;
 
+#ifdef JCS_EXTENSIONS
+  if (dec->format_convert) {
+    format = dec->format;
+  } else
+#endif
+  {
     switch (clrspc) {
       case JCS_RGB:
         format = GST_VIDEO_FORMAT_RGB;
@@ -976,6 +1036,7 @@ gst_jpeg_dec_negotiate (GstJpegDec * dec, gint width, gint height, gint clrspc,
         format = GST_VIDEO_FORMAT_I420;
         break;
     }
+  }
 
   /* Compare to currently configured output state */
   outstate = gst_video_decoder_get_output_state (GST_VIDEO_DECODER (dec));
@@ -990,6 +1051,50 @@ gst_jpeg_dec_negotiate (GstJpegDec * dec, gint width, gint height, gint clrspc,
     }
     gst_video_codec_state_unref (outstate);
   }
+#ifdef JCS_EXTENSIONS
+  dec_caps = gst_static_caps_get (&gst_jpeg_dec_src_pad_template.static_caps);
+  peer_caps =
+      gst_pad_peer_query_caps (GST_VIDEO_DECODER_SRC_PAD (dec), dec_caps);
+  gst_caps_unref (dec_caps);
+
+  GST_DEBUG ("Received caps from peer: %" GST_PTR_FORMAT, peer_caps);
+  dec->format_convert = FALSE;
+  if (!gst_caps_is_empty (peer_caps)) {
+    GstStructure *peerstruct;
+    const gchar *peerformat;
+    GstVideoFormat peerfmt;
+
+    if (!gst_caps_is_fixed (peer_caps))
+      peer_caps = gst_caps_fixate (peer_caps);
+
+    peerstruct = gst_caps_get_structure (peer_caps, 0);
+    peerformat = gst_structure_get_string (peerstruct, "format");
+    peerfmt = gst_video_format_from_string (peerformat);
+
+    switch (peerfmt) {
+      case GST_VIDEO_FORMAT_RGB:
+      case GST_VIDEO_FORMAT_RGBx:
+      case GST_VIDEO_FORMAT_xRGB:
+      case GST_VIDEO_FORMAT_RGBA:
+      case GST_VIDEO_FORMAT_ARGB:
+      case GST_VIDEO_FORMAT_BGR:
+      case GST_VIDEO_FORMAT_BGRx:
+      case GST_VIDEO_FORMAT_xBGR:
+      case GST_VIDEO_FORMAT_BGRA:
+      case GST_VIDEO_FORMAT_ABGR:
+        clrspc = JCS_RGB;
+        format = peerfmt;
+        dec->format_convert = TRUE;
+        dec->libjpeg_ext_format = gst_fmt_to_jpeg_turbo_ext_fmt (peerfmt);
+        break;
+      default:
+        break;
+    }
+  }
+  dec->format = format;
+  gst_caps_unref (peer_caps);
+  GST_DEBUG_OBJECT (dec, "format_convert=%d", dec->format_convert);
+#endif
 
   outstate =
       gst_video_decoder_set_output_state (GST_VIDEO_DECODER (dec), format,
@@ -1072,9 +1177,17 @@ gst_jpeg_dec_prepare_decode (GstJpegDec * dec)
   /* prepare for raw output */
   dec->cinfo.do_fancy_upsampling = FALSE;
   dec->cinfo.do_block_smoothing = FALSE;
-  dec->cinfo.out_color_space = dec->cinfo.jpeg_color_space;
   dec->cinfo.dct_method = dec->idct_method;
+#ifdef JCS_EXTENSIONS
+  if (dec->format_convert) {
+    dec->cinfo.out_color_space = dec->libjpeg_ext_format;
+    dec->cinfo.raw_data_out = FALSE;
+  } else
+#endif
+  {
+    dec->cinfo.out_color_space = dec->cinfo.jpeg_color_space;
     dec->cinfo.raw_data_out = TRUE;
+  }
 
   GST_LOG_OBJECT (dec, "starting decompress");
   guarantee_huff_tables (&dec->cinfo);
@@ -1347,6 +1460,12 @@ gst_jpeg_dec_handle_frame (GstVideoDecoder * bdec, GstVideoCodecFrame * frame)
     }
 
     /* check if format has changed for the second field */
+#ifdef JCS_EXTENSIONS
+    if (dec->format_convert) {
+      field2_format = dec->format;
+    } else
+#endif
+    {
       switch (dec->cinfo.jpeg_color_space) {
         case JCS_RGB:
           field2_format = GST_VIDEO_FORMAT_RGB;
@@ -1358,6 +1477,7 @@ gst_jpeg_dec_handle_frame (GstVideoDecoder * bdec, GstVideoCodecFrame * frame)
           field2_format = GST_VIDEO_FORMAT_I420;
           break;
       }
+    }
 
     GST_LOG_OBJECT (dec,
         "got for second field of interlaced image: "
@@ -1510,6 +1630,9 @@ gst_jpeg_dec_start (GstVideoDecoder * bdec)
 {
   GstJpegDec *dec = (GstJpegDec *) bdec;
 
+#ifdef JCS_EXTENSIONS
+  dec->format_convert = FALSE;
+#endif
   dec->saw_header = FALSE;
   dec->parse_entropy_len = 0;
   dec->parse_resync = FALSE;
@@ -1528,6 +1651,9 @@ gst_jpeg_dec_flush (GstVideoDecoder * bdec)
   dec->parse_entropy_len = 0;
   dec->parse_resync = FALSE;
   dec->saw_header = FALSE;
+#ifdef JCS_EXTENSIONS
+  dec->format_convert = FALSE;
+#endif
 
   return TRUE;
 }

subprojects/gst-plugins-good/ext/jpeg/gstjpegdec.h

@@ -74,6 +74,13 @@ struct _GstJpegDec {
   GstVideoCodecFrame *current_frame;
   GstMapInfo current_frame_map;
 
+  /* libjpeg-turbo colorspace conversion */
+#ifdef JCS_EXTENSIONS
+  GstVideoFormat format;
+  J_COLOR_SPACE libjpeg_ext_format;
+  gboolean format_convert;
+#endif
+
   /* parse state */
   gboolean saw_header;
   gint     parse_entropy_len;