24e526e09a
Move the ffmpeg -ss (seek/offset) parameter before -i in all transcoding commands so ffmpeg uses input seeking instead of output seeking. Per the ffmpeg docs, placing -ss before -i seeks at the demuxer level by keyframe (very fast), and since FFmpeg 2.1 it is also frame-accurate when transcoding. The previous placement after -i caused ffmpeg to decode and discard all audio up to the seek point, which was unnecessarily slow — especially problematic for lengthy files (4+ hours). Both code paths are updated: buildDynamicArgs (for default formats) and createFFmpegCommand (for custom templates without %t). A database migration updates existing default commands in the transcoding table.
55 lines
1.6 KiB
Go
55 lines
1.6 KiB
Go
package migrations
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import (
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"context"
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"database/sql"
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"github.com/pressly/goose/v3"
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)
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func init() {
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goose.AddMigrationContext(upMoveSsBeforeInput, downMoveSsBeforeInput)
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}
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// ssSeekPairs maps old commands (output seeking) to new commands (input seeking).
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// Index 0 = old (after -i), index 1 = new (before -i).
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var ssSeekPairs = [][2]string{
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{
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"ffmpeg -i %s -ss %t -map 0:a:0 -b:a %bk -v 0 -f mp3 -",
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"ffmpeg -ss %t -i %s -map 0:a:0 -b:a %bk -v 0 -f mp3 -",
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},
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{
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"ffmpeg -i %s -ss %t -map 0:a:0 -b:a %bk -v 0 -c:a libopus -f opus -",
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"ffmpeg -ss %t -i %s -map 0:a:0 -b:a %bk -v 0 -c:a libopus -f opus -",
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},
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{
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"ffmpeg -i %s -ss %t -map 0:a:0 -b:a %bk -v 0 -c:a aac -f adts -",
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"ffmpeg -ss %t -i %s -map 0:a:0 -b:a %bk -v 0 -c:a aac -f adts -",
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},
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{
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"ffmpeg -i %s -ss %t -map 0:a:0 -b:a %bk -v 0 -c:a aac -f ipod -movflags frag_keyframe+empty_moov -",
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"ffmpeg -ss %t -i %s -map 0:a:0 -b:a %bk -v 0 -c:a aac -f ipod -movflags frag_keyframe+empty_moov -",
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},
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{
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"ffmpeg -i %s -ss %t -map 0:a:0 -v 0 -c:a flac -f flac -",
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"ffmpeg -ss %t -i %s -map 0:a:0 -v 0 -c:a flac -f flac -",
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},
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}
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func upMoveSsBeforeInput(_ context.Context, tx *sql.Tx) error {
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for _, p := range ssSeekPairs {
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if _, err := tx.Exec(`UPDATE transcoding SET command = ? WHERE command = ?`, p[1], p[0]); err != nil {
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return err
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}
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}
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return nil
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}
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func downMoveSsBeforeInput(_ context.Context, tx *sql.Tx) error {
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for _, p := range ssSeekPairs {
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if _, err := tx.Exec(`UPDATE transcoding SET command = ? WHERE command = ?`, p[0], p[1]); err != nil {
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return err
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}
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}
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return nil
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}
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