FFmpeg interface improvements

This patch changes a couple of things in the video output encoding.

{F362527}

- Clearer separation between container and codec. No more "format", as this is
  too ambiguous. As a result, codecs were removed from the container list.
- Added FFmpeg speed presets, so the user can choosen from the range "Very
  slow" to "Ultra fast". By default no preset is used.
- Added Constant Rate Factor (CRF) mode, which allows changing the bit-rate
  depending on the desired quality and the input. This generally produces the
  best quality videos, at the expense of not knowing the exact bit-rate and
  file size.
- Added optional maximum of non-B-frames between B-frames (`max_b_frames`).
- Presets were adjusted for these changes, and new presets added. One of the
  new presets is [recommended](https://trac.ffmpeg.org/wiki/Encode/VFX#H.264)
  for reviewing videos, as it allows players to scrub through it easily. Might
  be nice in weeklies. This preset also requires control over the
  `max_b_frames` setting.

GUI-only changes:
- Renamed "MPEG" in the output file format menu with "FFmpeg", as this is more
  accurate. After all, FFmpeg is used when this option is chosen, which can
  also output non-MPEG files.
- Certain parts of the GUI are disabled when not in use:
    - bit rate options are not used when a constant rate factor is given.
    - audio bitrate & volume are not used when no audio is exported.

Note that I did not touch `BKE_ffmpeg_preset_set()`. There are currently two
preset systems for FFmpeg (`BKE_ffmpeg_preset_set()` and the Python preset
system). Before we do more work on `BKE_ffmpeg_preset_set()`, I think it's a
good idea to determine whether we want to keep it at all.

After this patch has been accepted, I'd be happy to go through the code and
remove any then-obsolete bits, such as the handling of "XVID" as a container
format.

Reviewers: sergey, mont29, brecht

Subscribers: mpan3, Blendify, brecht, fsiddi

Tags: #bf_blender

Differential Revision: https://developer.blender.org/D2242

release/scripts/startup/bl_ui/properties_render.py

@@ -461,31 +461,42 @@ class RENDER_PT_encoding(RenderButtonsPanel, Panel):
 
         split = layout.split()
         split.prop(rd.ffmpeg, "format")
-        if ffmpeg.format in {'AVI', 'QUICKTIME', 'MKV', 'OGG', 'MPEG4'}:
-            split.prop(ffmpeg, "codec")
-            if ffmpeg.codec == 'H264':
-                row = layout.row()
-                row.label()
-                row.prop(ffmpeg, "use_lossless_output")
-        elif rd.ffmpeg.format == 'H264':
-            split.prop(ffmpeg, "use_lossless_output")
-        else:
-            split.label()
+        split.prop(ffmpeg, "use_autosplit")
 
+        layout.separator()
+
+        needs_codec = ffmpeg.format in {'AVI', 'QUICKTIME', 'MKV', 'OGG', 'MPEG4'}
+        if needs_codec:
+            layout.prop(ffmpeg, "codec")
+
+        if ffmpeg.codec in {'DNXHD'}:
+            layout.prop(ffmpeg, "use_lossless_output")
+
+        # Output quality
+        if needs_codec and ffmpeg.codec in {'H264', 'MPEG4'}:
+            layout.prop(ffmpeg, "constant_rate_factor")
+
+        # Encoding speed
+        layout.prop(ffmpeg, "ffmpeg_preset")
+        # I-frames
+        layout.prop(ffmpeg, "gopsize")
+        # B-Frames
         row = layout.row()
-        row.prop(ffmpeg, "video_bitrate")
-        row.prop(ffmpeg, "gopsize")
+        row.prop(ffmpeg, "use_max_b_frames", text='Max B-frames')
+        pbox = row.split()
+        pbox.prop(ffmpeg, "max_b_frames", text='')
+        pbox.enabled = ffmpeg.use_max_b_frames
 
         split = layout.split()
-
+        split.enabled = ffmpeg.constant_rate_factor == 'NONE'
         col = split.column()
         col.label(text="Rate:")
+        col.prop(ffmpeg, "video_bitrate")
         col.prop(ffmpeg, "minrate", text="Minimum")
         col.prop(ffmpeg, "maxrate", text="Maximum")
         col.prop(ffmpeg, "buffersize", text="Buffer")
 
         col = split.column()
-        col.prop(ffmpeg, "use_autosplit")
         col.label(text="Mux:")
         col.prop(ffmpeg, "muxrate", text="Rate")
         col.prop(ffmpeg, "packetsize", text="Packet Size")
@@ -497,6 +508,7 @@ class RENDER_PT_encoding(RenderButtonsPanel, Panel):
             layout.prop(ffmpeg, "audio_codec", text="Audio Codec")
 
         row = layout.row()
+        row.enabled = ffmpeg.audio_codec != 'NONE'
         row.prop(ffmpeg, "audio_bitrate")
         row.prop(ffmpeg, "audio_volume", slider=True)