Map vp9 --preset to -cpu-used

Error when setting reserved --enc,enc-input args
Avoid overriding --enc b:a, movflags, ac
Resolves #45
Resolves #46

CHANGELOG.md

@@ -1,3 +1,9 @@
+# Unreleased (v0.4.1)
+* For `-e libvpx-vp9` map `--preset` number to ffmpeg `-cpu-used` (0-5).
+* When overriding with a ffmpeg encoder avoid setting `b:a`, `movflags` or `ac` if explicitly set via `--enc`.
+* Add error output when using `--enc-input` with the default svt-av1 encoder.
+* Add errors for `--enc`/`--enc-input` args that are already provided by existing args or inferred.
+
 # v0.4.0
 * Add `--encoder`/`-e` encoder override. 
   Any [encoder ffmpeg supports](https://ffmpeg.org/ffmpeg-all.html#toc-Video-Encoders)

src/command/args/encode.rs

@@ -6,6 +6,7 @@ use crate::{
 use anyhow::ensure;
 use clap::Parser;
 use std::{
+    collections::HashMap,
     fmt::{self, Write},
     path::PathBuf,
     sync::Arc,
@@ -289,6 +290,29 @@ impl Encode {
             })
             .collect();
 
+        // ban usage of the bits we already set via other args & logic
+        let reserved = HashMap::from([
+            ("-c:a", " use --acodec"),
+            ("-codec:a", " use --acodec"),
+            ("-acodec", " use --acodec"),
+            ("-i", ""),
+            ("-y", ""),
+            ("-n", ""),
+            ("-c:v", ""),
+            ("-codec:v", ""),
+            ("-vcodec", ""),
+            ("-pix_fmt", " use --pix-format"),
+            ("-crf", ""),
+            ("-preset", " use --preset"),
+            ("-vf", " use --vfilter"),
+            ("-filter:v", " use --vfilter"),
+        ]);
+        for arg in args.iter().chain(input_args.iter()) {
+            if let Some(hint) = reserved.get(arg.as_str()) {
+                anyhow::bail!("Encoder argument `{arg}` not allowed{hint}");
+            }
+        }
+
         Ok(FfmpegEncodeArgs {
             input: &self.input,
             vcodec,

src/ffmpeg.rs

@@ -7,6 +7,7 @@ use crate::{
 };
 use anyhow::Context;
 use std::{
+    collections::HashSet,
     path::{Path, PathBuf},
     process::Stdio,
     sync::Arc,
@@ -95,12 +96,18 @@ pub fn encode(
     audio_codec: Option<&str>,
     downmix_to_stereo: bool,
 ) -> anyhow::Result<impl Stream<Item = anyhow::Result<FfmpegOut>>> {
-    let output_is_mp4 = output.extension().and_then(|e| e.to_str()) == Some("mp4");
+    let oargs: HashSet<_> = output_args.iter().map(|a| a.as_str()).collect();
+
+    let add_faststart =
+        output.extension().and_then(|e| e.to_str()) == Some("mp4") && !oargs.contains("-movflags");
 
     let audio_codec = audio_codec.unwrap_or_else(|| {
         svtav1::default_audio_codec(input, output, downmix_to_stereo, has_audio)
     });
 
+    let set_ba_128k = audio_codec == "libopus" && !oargs.contains("-b:a");
+    let downmix_to_stereo = downmix_to_stereo && !oargs.contains("-ac");
+
     let enc = Command::new("ffmpeg")
         .kill_on_drop(true)
         .args(input_args.iter().map(|a| &**a))
@@ -115,8 +122,8 @@ pub fn encode(
         .arg2("-c:s", "copy")
         .arg2("-c:a", audio_codec)
         .arg2_if(downmix_to_stereo, "-ac", 2)
-        .arg2_if(audio_codec == "libopus", "-b:a", "128k")
-        .arg2_if(output_is_mp4, "-movflags", "+faststart")
+        .arg2_if(set_ba_128k, "-b:a", "128k")
+        .arg2_if(add_faststart, "-movflags", "+faststart")
         .arg(output)
         .stdout(Stdio::null())
         .stderr(Stdio::piped())
@@ -144,7 +151,7 @@ trait VCodecSpecific {
 impl VCodecSpecific for Arc<str> {
     fn preset_arg(&self) -> &str {
         match &**self {
-            "libaom-av1" => "-cpu-used",
+            "libaom-av1" | "libvpx-vp9" => "-cpu-used",
             _ => "-preset",
         }
     }

src/svtav1.rs

@@ -92,7 +92,7 @@ pub fn encode(
     audio_codec: Option<&str>,
     downmix_to_stereo: bool,
 ) -> anyhow::Result<impl Stream<Item = anyhow::Result<FfmpegOut>>> {
-    let output_is_mp4 = output.extension().and_then(|e| e.to_str()) == Some("mp4");
+    let add_faststart = output.extension().and_then(|e| e.to_str()) == Some("mp4");
 
     let audio_codec = audio_codec
         .unwrap_or_else(|| default_audio_codec(input, output, downmix_to_stereo, has_audio));
@@ -139,7 +139,7 @@ pub fn encode(
         .arg2_if(downmix_to_stereo, "-ac", 2)
         .arg2("-c:v", "copy")
         .arg2_if(audio_codec == "libopus", "-b:a", "128k")
-        .arg2_if(output_is_mp4, "-movflags", "+faststart")
+        .arg2_if(add_faststart, "-movflags", "+faststart")
         .arg(output)
         .spawn()
         .context("ffmpeg to-output")?;