acfunlive-remake/fps_test.go

package main

import (
	"math"
	"path/filepath"
	"testing"
)

// 输出帧率只在目标的**上面**才生效：源片本来就 60fps 时填 30 只会把画面压得更卡，
// 源片帧率探测不到（0）时也不动，免得把高帧率源押到某个值
func TestOutputFpsOnlyRaises(t *testing.T) {
	for _, c := range []struct {
		target int
		source float64
		want   int
	}{
		{0, 30, 0},      // 没填：跟随源片
		{60, 0, 0},      // 源片帧率探测不到：不动
		{60, 30, 60},    // 15/24/30fps 录播里弹幕一格一格跳，提上去
		{60, 60, 0},     // 已经一样高：不动
		{60, 59.94, 60}, // 29.97/59.94 这类小数帧率要当成「低一点点」
		{30, 60, 0},     // 降帧没意义
		{-1, 30, 0},     // 非法值当成没填
	} {
		if got := outputFps(c.target, c.source); got != c.want {
			t.Errorf("outputFps(%d, %g) = %d，期望 %d", c.target, c.source, got, c.want)
		}
	}
}

// 透明头像层模式没有源片可跟：设置填了就按填的，没填固定 30
func TestLayerFpsFallback(t *testing.T) {
	if got := layerFps(0); got != defaultLayerFps {
		t.Errorf("layerFps(0) = %d，期望 %d", got, defaultLayerFps)
	}
	if got := layerFps(60); got != 60 {
		t.Errorf("layerFps(60) = %d，期望 60", got)
	}
	// 手工构造的 burnContext 没填这个字段时也不能把 r=0 交给 ffmpeg
	// （color 源拿 r=0 会直接 EINVAL，症状是 exit status 0xffffffea）
	ctx := &burnContext{}
	if got := ctx.layerRate(); got != defaultLayerFps {
		t.Errorf("没填 layerFps 的 burnContext 应当回落到 %d，实际 %d", defaultLayerFps, got)
	}
	ctx.layerFps = 25
	if got := ctx.layerRate(); got != 25 {
		t.Errorf("填了 layerFps 就按填的来，实际 %d", got)
	}
}

// 低帧率源设了输出帧率时，成片帧率真的会提上去：
// fps 滤镜必须加在字幕/头像之前，弹幕才会按新帧率重绘；
// 加在之后只是把已经画好的几帧复制一遍，看起来还是卡
func TestRenderChunkRaisesFrameRate(t *testing.T) {
	ffmpegFile := getFFmpeg()
	if ffmpegFile == "" {
		t.Skip("找不到 ffmpeg，跳过")
	}
	withJobFlags(t, true, false, false)
	dir := t.TempDir()

	src := filepath.Join(dir, "src.mp4")
	if err := runFFmpegWith(ffmpegFile, []string{
		"-y", "-f", "lavfi", "-i", "color=c=black:s=160x120:d=1:r=15",
		"-c:v", "libx264", "-pix_fmt", "yuv420p", src,
	}, dir, nil); err != nil {
		t.Skipf("生成 15fps 测试视频失败，跳过：%v", err)
	}

	chunk := danmuChunk{start: 0, end: 1, records: []danmuRecord{
		{Time: 0.1, UID: 7, Name: "甲", Content: "提帧测试", Lane: 0, Width: 100},
	}}
	ctx := &burnContext{
		ffmpegFile: ffmpegFile,
		videoFile:  src,
		outFile:    filepath.Join(dir, "out.mp4"),
		meta:       danmuMeta{PlayResX: 160, PlayResY: 120, FontSize: 20},
		avatars:    map[int64]string{},
		dir:        dir,
		encoder:    "libx264",
		outFps:     outputFps(30, 15),
	}
	if ctx.outFps != 30 {
		t.Fatalf("15fps 源设 30 应当产出 outFps=30，实际 %d", ctx.outFps)
	}

	assName := chunkTempPrefix + "fps_test.ass"
	if err := writeChunkAss(filepath.Join(dir, assName), ctx.meta, chunk, 0,
		avatarSize(ctx.meta.FontSize), avatarGap(ctx.meta.FontSize)); err != nil {
		t.Fatal(err)
	}

	out := filepath.Join(dir, "chunk.mp4")
	if err := ctx.renderChunk(chunk, assName, out, true, nil); err != nil {
		t.Fatalf("提帧渲染不该失败：%v", err)
	}
	info := probeVideoStream(ffmpegFile, out)
	if math.Abs(info.fps-30) > 0.5 {
		t.Fatalf("成片帧率应当是 30，实际 %.2f", info.fps)
	}
}