From 26013077affafc6160a64bc875762c02f0c3ca89 Mon Sep 17 00:00:00 2001
From: Mikael Finstad <finstaden@gmail.com>
Date: Fri, 30 Jan 2026 13:44:59 +0800
Subject: [PATCH] add smartcut option `-bf` based on `has_b_frames`

#2690 #126
---
 src/renderer/src/hooks/useFfmpegOperations.ts | 7 +++++--
 src/renderer/src/smartcut.ts                  | 2 +-
 2 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/src/renderer/src/hooks/useFfmpegOperations.ts b/src/renderer/src/hooks/useFfmpegOperations.ts
index 996fbfb5..f8fa41f8 100644
--- a/src/renderer/src/hooks/useFfmpegOperations.ts
+++ b/src/renderer/src/hooks/useFfmpegOperations.ts
@@ -427,7 +427,7 @@ function useFfmpegOperations({ filePath, treatInputFileModifiedTimeAsStart, trea
   }, [appendFfmpegCommandLog, cutFromAdjustmentFrames, cutToAdjustmentFrames, filePath, getOutputPlaybackRateArgs, treatInputFileModifiedTimeAsStart, treatOutputFileModifiedTimeAsStart]);
 
   // inspired by https://gist.github.com/fernandoherreradelasheras/5eca67f4200f1a7cc8281747da08496e
-  const cutEncodeSmartPart = useCallback(async ({ cutFrom, cutTo, outPath, outFormat, videoCodec, videoBitrate, videoTimebase, allFilesMeta, copyFileStreams, videoStreamIndex, ffmpegExperimental }: {
+  const cutEncodeSmartPart = useCallback(async ({ cutFrom, cutTo, outPath, outFormat, videoCodec, videoBitrate, videoTimebase, allFilesMeta, copyFileStreams, videoStreamIndex, ffmpegExperimental, hasBFrames }: {
     cutFrom: number,
     cutTo: number,
     outPath: string,
@@ -439,6 +439,7 @@ function useFfmpegOperations({ filePath, treatInputFileModifiedTimeAsStart, trea
     copyFileStreams: CopyfileStreams,
     videoStreamIndex: number,
     ffmpegExperimental: boolean,
+    hasBFrames: number | undefined,
   }) => {
     invariant(filePath != null);
 
@@ -481,6 +482,8 @@ function useFfmpegOperations({ filePath, treatInputFileModifiedTimeAsStart, trea
 
       ...getVideoTimescaleArgs(videoTimebase),
 
+      ...(hasBFrames ? ['-bf', String(hasBFrames)] : []),
+
       ...getExperimentalArgs(ffmpegExperimental),
 
       '-f', outFormat, '-y', outPath,
@@ -583,7 +586,7 @@ function useFfmpegOperations({ filePath, treatInputFileModifiedTimeAsStart, trea
         invariant(sourceCodecParams.videoTimebase != null);
         invariant(filePath != null);
         invariant(outFormat != null);
-        await cutEncodeSmartPart({ cutFrom, cutTo, outPath, outFormat, videoCodec, videoBitrate: encCustomBitrate != null ? encCustomBitrate * 1000 : sourceCodecParams.videoBitrate, videoStreamIndex: videoStream.index, videoTimebase: sourceCodecParams.videoTimebase, allFilesMeta, copyFileStreams: copyFileStreamsFiltered, ffmpegExperimental });
+        await cutEncodeSmartPart({ cutFrom, cutTo, outPath, outFormat, videoCodec, videoBitrate: encCustomBitrate != null ? encCustomBitrate * 1000 : sourceCodecParams.videoBitrate, videoStreamIndex: videoStream.index, videoTimebase: sourceCodecParams.videoTimebase, allFilesMeta, copyFileStreams: copyFileStreamsFiltered, ffmpegExperimental, hasBFrames: sourceCodecParams.videoStream.has_b_frames });
       }
 
       const cutEncodeWholePart = async () => {
diff --git a/src/renderer/src/smartcut.ts b/src/renderer/src/smartcut.ts
index 20c02e08..4d18892c 100644
--- a/src/renderer/src/smartcut.ts
+++ b/src/renderer/src/smartcut.ts
@@ -50,7 +50,7 @@ export async function needsSmartCut({ path, desiredCutFrom, videoStream }: {
 export async function getCodecParams({ path, fileDuration, streams }: {
   path: string,
   fileDuration: number | undefined,
-  streams: Pick<FFprobeStream, 'time_base' | 'codec_type' | 'disposition' | 'index' | 'bit_rate' | 'codec_name'>[],
+  streams: Pick<FFprobeStream, 'has_b_frames' | 'time_base' | 'codec_type' | 'disposition' | 'index' | 'bit_rate' | 'codec_name'>[],
 }) {
   const videoStreams = getRealVideoStreams(streams);
   if (videoStreams.length > 1) throw new Error('Can only smart cut video with exactly one video stream');