From c50584b8d150a1abefd749c56dc3cbab9e773c03 Mon Sep 17 00:00:00 2001
From: Alex Butler <alexheretic@gmail.com>
Date: Sun, 22 Dec 2024 15:22:03 +0000
Subject: [PATCH] Add defaults for mpeg2video encoder

---
 CHANGELOG.md               |  1 +
 src/command/args/encode.rs |  8 ++++++++
 src/command/crf_search.rs  | 13 ++++++++-----
 src/ffmpeg.rs              |  3 ++-
 4 files changed, 19 insertions(+), 6 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 4228147..c180497 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,7 @@
 # Unreleased (0.8.1)
 * Support negative `--preset` args.
 * Add `--vmaf-fps`: Frame rate override used to analyse both reference & distorted videos.
+* mpeg2video: map `--crf` to ffmpeg `-q` and set default crf range to 2-30.
 
 # v0.8.0
 * crf-search: Tweak 2nd iteration logic that slices the crf range at the 25% or 75% crf point.
diff --git a/src/command/args/encode.rs b/src/command/args/encode.rs
index ba22638..a3eb6ba 100644
--- a/src/command/args/encode.rs
+++ b/src/command/args/encode.rs
@@ -341,11 +341,19 @@ impl Encoder {
         }
     }
 
+    pub fn default_min_crf(&self) -> f32 {
+        match self.as_str() {
+            "mpeg2video" => 2.0,
+            _ => 10.0,
+        }
+    }
+
     pub fn default_max_crf(&self) -> f32 {
         match self.as_str() {
             "libx264" | "libx265" => 46.0,
             "librav1e" => 255.0,
             "av1_vaapi" => 255.0,
+            "mpeg2video" => 30.0,
             // Works well for svt-av1
             _ => 55.0,
         }
diff --git a/src/command/crf_search.rs b/src/command/crf_search.rs
index 7540f2f..e20c1f6 100644
--- a/src/command/crf_search.rs
+++ b/src/command/crf_search.rs
@@ -26,7 +26,6 @@ use std::{
 };
 
 const BAR_LEN: u64 = 1024 * 1024 * 1024;
-const DEFAULT_MIN_CRF: f32 = 10.0;
 
 /// Interpolated binary search using sample-encode to find the best crf
 /// value delivering min-vmaf & max-encoded-percent.
@@ -54,12 +53,14 @@ pub struct Args {
     pub max_encoded_percent: f32,
 
     /// Minimum (highest quality) crf value to try.
-    #[arg(long, default_value_t = DEFAULT_MIN_CRF)]
-    pub min_crf: f32,
+    ///
+    /// [default: 10, 2 for mpeg2video]
+    #[arg(long)]
+    pub min_crf: Option<f32>,
 
     /// Maximum (lowest quality) crf value to try.
     ///
-    /// [default: 55, 46 for x264,x265, 255 for rav1e,av1_vaapi]
+    /// [default: 55, 46 for x264,x265, 255 for rav1e,av1_vaapi, 30 for mpeg2video]
     #[arg(long)]
     pub max_crf: Option<f32>,
 
@@ -198,6 +199,8 @@ pub fn run(
     async_stream::try_stream! {
         let default_max_crf = args.encoder.default_max_crf();
         let max_crf = max_crf.unwrap_or(default_max_crf);
+        let default_min_crf = args.encoder.default_min_crf();
+        let min_crf = min_crf.unwrap_or(default_min_crf);
         Error::ensure_other(min_crf < max_crf, "Invalid --min-crf & --max-crf")?;
 
         // Whether to make the 2nd iteration on the ~20%/~80% crf point instead of the min/max to
@@ -208,7 +211,7 @@ pub fn run(
         // the min/max crf on the 3rd iter.
         //
         // If a custom crf range is being used under half the default, this 2nd cut is not needed.
-        let cut_on_iter2 = (max_crf - min_crf) > (default_max_crf - DEFAULT_MIN_CRF) * 0.5;
+        let cut_on_iter2 = (max_crf - min_crf) > (default_max_crf - default_min_crf) * 0.5;
 
         let crf_increment = crf_increment
             .unwrap_or_else(|| args.encoder.default_crf_increment())
diff --git a/src/ffmpeg.rs b/src/ffmpeg.rs
index 69c7121..5352017 100644
--- a/src/ffmpeg.rs
+++ b/src/ffmpeg.rs
@@ -204,10 +204,11 @@ impl VCodecSpecific for Arc<str> {
     }
 
     fn crf_arg(&self) -> &str {
-        // // use crf-like args to support encoders that don't have crf
+        // use crf-like args to support encoders that don't have crf
         match &**self {
             // https://ffmpeg.org//ffmpeg-codecs.html#librav1e
             "librav1e" => "-qp",
+            "mpeg2video" => "-q",
             // https://ffmpeg.org//ffmpeg-codecs.html#VAAPI-encoders
             e if e.ends_with("_vaapi") => "-q",
             e if e.ends_with("_nvenc") => "-cq",