Specify unspecified gamma instead of lying and saying we use Rec. 709. Again, for...

diff --git a/h264encode.cpp b/h264encode.cpp
index 4b900bfdab3f468704d4a3b2689980b19a338748..74b51910856b86aacea8999bdda45ec978ea3662 100644 (file)
--- a/h264encode.cpp
+++ b/h264encode.cpp
@@ -347,7 +347,7 @@ static void sps_rbsp(bitstream *bs)
             bitstream_put_ui(bs, 1, 1);  /* colour_description_present_flag */
             {
                 bitstream_put_ui(bs, 1, 8);  /* colour_primaries (1 = BT.709) */
-                bitstream_put_ui(bs, 1, 8);  /* transfer_characteristics (1 = BT.709) */
+                bitstream_put_ui(bs, 2, 8);  /* transfer_characteristics (2 = unspecified, since we use sRGB) */
                 bitstream_put_ui(bs, 6, 8);  /* matrix_coefficients (6 = BT.601/SMPTE 170M) */
             }
         }

diff --git a/httpd.cpp b/httpd.cpp
index 57218841c73e99459e4fbe04cb73df78f4a333a4..f266c63656d17cb14cce47c4886573159d61e5da 100644 (file)
--- a/httpd.cpp
+++ b/httpd.cpp
@@ -94,7 +94,7 @@ HTTPD::Mux::Mux(AVFormatContext *avctx, int width, int height)
        // Note that the H.264 stream also contains this information and depending on the
        // mux, this might simply get ignored. See sps_rbsp().
        avstream_video->codec->color_primaries = AVCOL_PRI_BT709;  // RGB colorspace (inout_format.color_space).
-       avstream_video->codec->color_trc = AVCOL_TRC_BT709;  // Gamma curve (inout_format.gamma_curve).
+       avstream_video->codec->color_trc = AVCOL_TRC_UNSPECIFIED;  // Gamma curve (inout_format.gamma_curve).
        avstream_video->codec->colorspace = AVCOL_SPC_SMPTE170M;  // YUV colorspace (output_ycbcr_format.luma_coefficients).
        avstream_video->codec->color_range = AVCOL_RANGE_MPEG;  // Full vs. limited range (output_ycbcr_format.full_range).
        avstream_video->codec->chroma_sample_location = AVCHROMA_LOC_LEFT;  // Chroma sample location. See chroma_offset_0[] in Mixer::subsample_chroma().

diff --git a/theme.cpp b/theme.cpp
index 2c9af01cf69b36cc150d0f98c6140cefa814b650..9914952948477e1a6223f23e298057b9ba34a691 100644 (file)
--- a/theme.cpp
+++ b/theme.cpp
@@ -129,12 +129,10 @@ int EffectChain_finalize(lua_State* L)
        ImageFormat inout_format;
        inout_format.color_space = COLORSPACE_REC_709;
 
-       // Gamma curve depends on the input signal, and we don't really get any
-       // indications. A camera would be expected to do Rec. 709, but
-       // I haven't checked if any do in practice. However, computers _do_ output
-       // in sRGB gamma (ie., they don't convert from sRGB to Rec. 709), and
-       // I wouldn't really be surprised if most non-professional cameras do, too.
-       // So we pick sRGB as the least evil here.
+       // Output gamma is tricky. We should output Rec. 709 for TV, except that
+       // we expect to run with web players and others that don't really care and
+       // just output with no conversion. So that means we'll need to output sRGB,
+       // even though H.264 has no setting for that (we use “unspecified”).
        inout_format.gamma_curve = GAMMA_sRGB;
 
        if (is_main_chain) {
@@ -337,6 +335,13 @@ LiveInputWrapper::LiveInputWrapper(Theme *theme, EffectChain *chain, bool overri
 {
        ImageFormat inout_format;
        inout_format.color_space = COLORSPACE_sRGB;
+
+       // Gamma curve depends on the input signal, and we don't really get any
+       // indications. A camera would be expected to do Rec. 709, but
+       // I haven't checked if any do in practice. However, computers _do_ output
+       // in sRGB gamma (ie., they don't convert from sRGB to Rec. 709), and
+       // I wouldn't really be surprised if most non-professional cameras do, too.
+       // So we pick sRGB as the least evil here.
        inout_format.gamma_curve = GAMMA_sRGB;
 
        // The Blackmagic driver docs claim that the device outputs Y'CbCr