[FFmpeg-devel] [PATCH v2 03/13] fftools/ffmpeg_filter: auto-convert range if needed

[Niklas Haas]

From: Niklas Haas <git at haasn.dev>

To convert between color ranges, if needed by the codec properties. We
momentarily duplicate the mjpeg strictness logic to also enfoce full
range. This duplication will be cleaned up in the next commit.

Due to avcodec_open2 being called after ofilter_bind_ost, we need to
look up the eventual encoder options from the options dictionary
directly, following the same design as the "strict" option.
---
 fftools/ffmpeg_filter.c | 61 +++++++++++++++++++++++++++++++++++------
 1 file changed, 52 insertions(+), 9 deletions(-)

diff --git a/fftools/ffmpeg_filter.c b/fftools/ffmpeg_filter.c
index c738fc3397..acdfa72043 100644
--- a/fftools/ffmpeg_filter.c
+++ b/fftools/ffmpeg_filter.c
@@ -169,6 +169,7 @@ typedef struct OutputFilterPriv {
     int width, height;
     int sample_rate;
     AVChannelLayout ch_layout;
+    enum AVColorRange range;
 
     // time base in which the output is sent to our downstream
     // does not need to match the filtersink's timebase
@@ -184,6 +185,7 @@ typedef struct OutputFilterPriv {
     const int *formats;
     const AVChannelLayout *ch_layouts;
     const int *sample_rates;
+    const enum AVColorRange *ranges;
 
     AVRational enc_timebase;
     // offset for output timestamps, in AV_TIME_BASE_Q
@@ -368,6 +370,9 @@ DEF_CHOOSE_FORMAT(sample_fmts, enum AVSampleFormat, format, formats,
 DEF_CHOOSE_FORMAT(sample_rates, int, sample_rate, sample_rates, 0,
                   "%d", )
 
+DEF_CHOOSE_FORMAT(out_range, enum AVColorRange, range, ranges,
+                  AVCOL_RANGE_UNSPECIFIED, "%s", av_color_range_name);
+
 static void choose_channel_layouts(OutputFilterPriv *ofp, AVBPrint *bprint)
 {
     if (av_channel_layout_check(&ofp->ch_layout)) {
@@ -662,6 +667,17 @@ static int set_channel_layout(OutputFilterPriv *f, OutputStream *ost)
     return 0;
 }
 
+static int ost_opt_int(OutputStream *ost, const char *name, int defval)
+{
+    const AVDictionaryEntry *e = av_dict_get(ost->encoder_opts, name, NULL, 0);
+    if (e) {
+        const AVOption *o = av_opt_find(ost->enc_ctx, e->key, NULL, 0, 0);
+        av_assert0(o);
+        av_opt_eval_int(ost->enc_ctx, o, e->value, &defval);
+    }
+    return defval;
+}
+
 int ofilter_bind_ost(OutputFilter *ofilter, OutputStream *ost)
 {
     const OutputFile  *of = output_files[ost->file_index];
@@ -669,6 +685,7 @@ int ofilter_bind_ost(OutputFilter *ofilter, OutputStream *ost)
     FilterGraph  *fg = ofilter->graph;
     FilterGraphPriv *fgp = fgp_from_fg(fg);
     const AVCodec *c = ost->enc_ctx->codec;
+    enum AVColorRange color_range;
 
     av_assert0(!ofilter->ost);
 
@@ -682,6 +699,26 @@ int ofilter_bind_ost(OutputFilter *ofilter, OutputStream *ost)
     case AVMEDIA_TYPE_VIDEO:
         ofp->width      = ost->enc_ctx->width;
         ofp->height     = ost->enc_ctx->height;
+        color_range     = ost_opt_int(ost, "color_range", ost->enc_ctx->color_range);
+        if (color_range != AVCOL_RANGE_UNSPECIFIED) {
+            ofp->range = color_range;
+        } else {
+            ofp->ranges = c->color_ranges;
+
+            // MJPEG encoder exports a full list of supported pixel formats,
+            // but the full-range ones are experimental-only.
+            // Restrict the auto-conversion list unless -strict experimental
+            // has been specified.
+            if (!strcmp(c->name, "mjpeg")) {
+                static const enum AVColorRange mjpeg_ranges[] =
+                    { AVCOL_RANGE_JPEG, AVCOL_RANGE_UNSPECIFIED };
+
+                int strict_val = ost->enc_ctx->strict_std_compliance;
+                strict_val = ost_opt_int(ost, "strict", strict_val);
+                if (strict_val > FF_COMPLIANCE_UNOFFICIAL)
+                    ofp->ranges = mjpeg_ranges;
+            }
+        }
         if (ost->enc_ctx->pix_fmt != AV_PIX_FMT_NONE) {
             ofp->format = ost->enc_ctx->pix_fmt;
         } else {
@@ -1149,6 +1186,7 @@ static int configure_output_video_filter(FilterGraph *fg, OutputFilter *ofilter,
     OutputFilterPriv *ofp = ofp_from_ofilter(ofilter);
     OutputStream *ost = ofilter->ost;
     OutputFile    *of = output_files[ost->file_index];
+    FilterGraphPriv *fgp = fgp_from_fg(fg);
     AVFilterContext *last_filter = out->filter_ctx;
     AVBPrint bprint;
     int pad_idx = out->pad_idx;
@@ -1164,22 +1202,27 @@ static int configure_output_video_filter(FilterGraph *fg, OutputFilter *ofilter,
     if (ret < 0)
         return ret;
 
-    if ((ofp->width || ofp->height) && ofilter->ost->autoscale) {
-        char args[255];
+    av_bprint_init(&bprint, 0, AV_BPRINT_SIZE_UNLIMITED);
+    if ((ofp->width || ofp->height) && ofilter->ost->autoscale)
+        av_bprintf(&bprint, "w=%d:h=%d:", ofp->width, ofp->height);
+    if (!fgp->disable_conversions)
+        choose_out_range(ofp, &bprint);
+    if (bprint.len) {
         AVFilterContext *filter;
         const AVDictionaryEntry *e = NULL;
 
-        snprintf(args, sizeof(args), "%d:%d",
-                 ofp->width, ofp->height);
+        while ((e = av_dict_iterate(ost->sws_dict, e)))
+            av_bprintf(&bprint, "%s=%s:", e->key, e->value);
 
-        while ((e = av_dict_iterate(ost->sws_dict, e))) {
-            av_strlcatf(args, sizeof(args), ":%s=%s", e->key, e->value);
-        }
+        if (!av_bprint_is_complete(&bprint))
+            return AVERROR(ENOMEM);
 
         snprintf(name, sizeof(name), "scaler_out_%d_%d",
                  ost->file_index, ost->index);
-        if ((ret = avfilter_graph_create_filter(&filter, avfilter_get_by_name("scale"),
-                                                name, args, NULL, fg->graph)) < 0)
+        ret = avfilter_graph_create_filter(&filter, avfilter_get_by_name("scale"),
+                                           name, bprint.str, NULL, fg->graph);
+        av_bprint_finalize(&bprint, NULL);
+        if (ret < 0)
             return ret;
         if ((ret = avfilter_link(last_filter, pad_idx, filter, 0)) < 0)
             return ret;
-- 
2.42.0