1 files changed, 150 insertions, 0 deletions
diff --git a/src/ffmpeg.rs b/src/ffmpeg.rs
new file mode 100644
index 0000000..fbfdc94
--- /dev/null
+++ b/src/ffmpeg.rs
@@ -0,0 +1,150 @@
+use std::process::Command;
+
+/// Options that ffmpeg supports but ffprobe does not.
+const FFMPEG_ONLY_OPTIONS: &[&str] = &["-stream_loop", "-t"];
+
+const ALPHA_FMTS: &[&str] = &[
+    "pal8",
+    "argb",
+    "rgba",
+    "abgr",
+    "bgra",
+    "yuva420p",
+    "ya8",
+    "yuva422p",
+    "yuva444p",
+    "yuva420p9be",
+    "yuva420p9le",
+    "yuva422p9be",
+    "yuva422p9le",
+    "yuva444p9be",
+    "yuva444p9le",
+    "yuva420p10be",
+    "yuva420p10le",
+    "yuva422p10be",
+    "yuva422p10le",
+    "yuva444p10be",
+    "yuva444p10le",
+    "yuva420p16be",
+    "yuva420p16le",
+    "yuva422p16be",
+    "yuva422p16le",
+    "yuva444p16be",
+    "yuva444p16le",
+    "rgba64be",
+    "rgba64le",
+    "bgra64be",
+    "bgra64le",
+    "ya16be",
+    "ya16le",
+    "gbrap",
+    "gbrap16be",
+    "gbrap16le",
+    "ayuv64le",
+    "ayuv64be",
+    "gbrap12be",
+    "gbrap12le",
+    "gbrap10be",
+    "gbrap10le",
+    "gbrapf32be",
+    "gbrapf32le",
+    "yuva422p12be",
+    "yuva422p12le",
+    "yuva444p12be",
+    "yuva444p12le",
+    "vuya",
+    "rgbaf16be",
+    "rgbaf16le",
+    "rgbaf32be",
+    "rgbaf32le",
+    "gbrap14be",
+    "gbrap14le",
+    "ayuv",
+    "uyva",
+    "rgba128be",
+    "rgba128le",
+    "gbrapf16be",
+    "gbrapf16le",
+    "yaf32be",
+    "yaf32le",
+    "yaf16be",
+    "yaf16le",
+    "gbrap32be",
+    "gbrap32le",
+];
+
+fn filter_probe_args(ff_args: &[String]) -> Vec<String> {
+    let mut out = Vec::new();
+    let mut skip_next = false;
+    for arg in ff_args {
+        if skip_next {
+            skip_next = false;
+            continue;
+        }
+        if FFMPEG_ONLY_OPTIONS.contains(&arg.as_str()) {
+            skip_next = true;
+            continue;
+        }
+        out.push(arg.clone());
+    }
+    out
+}
+
+pub struct VideoInfo {
+    pub width: u32,
+    pub height: u32,
+    pub num_frames: Option<u32>,
+    pub fps: f64,
+    pub alpha: bool,
+    pub codec_tag: String,
+}
+
+pub fn probe_video(ff_args: &[String], max_frames: Option<u32>) -> VideoInfo {
+    let probe_args = filter_probe_args(ff_args);
+    let output = Command::new("ffprobe")
+        .args(["-v", "error"])
+        .args(["-select_streams", "v:0"])
+        .args([
+            "-show_entries",
+            "stream=codec_tag_string,width,height,pix_fmt,r_frame_rate,nb_frames",
+        ])
+        .args(["-of", "csv=p=0"])
+        .args(&probe_args)
+        .output()
+        .expect("failed to run ffprobe");
+
+    if !output.status.success() {
+        let stderr = String::from_utf8_lossy(&output.stderr);
+        panic!("ffprobe failed: {stderr}");
+    }
+
+    let stdout = String::from_utf8_lossy(&output.stdout);
+    let line = stdout.trim();
+    let parts: Vec<&str> = line.split(',').collect();
+    if parts.len() != 6 {
+        panic!("unexpected ffprobe output: {line}");
+    }
+
+    let codec_tag = parts[0].to_string();
+    let width: u32 = parts[1].parse().expect("parse width");
+    let height: u32 = parts[2].parse().expect("parse height");
+    let alpha = ALPHA_FMTS.contains(&parts[3]);
+
+    let fps: f64 = if let Some((num, den)) = parts[4].split_once('/') {
+        let n: f64 = num.parse().expect("parse fps numerator");
+        let d: f64 = den.parse().expect("parse fps denominator");
+        n / d
+    } else {
+        parts[4].parse().expect("parse fps")
+    };
+    let num_frames = parts[5].parse().ok().or(max_frames);
+
+    VideoInfo {
+        width,
+        height,
+        num_frames,
+        fps,
+        alpha,
+        codec_tag,
+    }
+}