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Mime type & MP3 improvements

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This commit is contained in:
Vanilagy
2025-02-02 17:21:57 +01:00
parent ffd0835e9a
commit 35c4d384cf
4 changed files with 24 additions and 7 deletions
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src/mp3/mp3-misc.ts
+8 -3
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@@ -46,8 +46,13 @@ export type FrameHeader = {
emphasis: number;
};
export const computeMp3FrameSize = (bitrate: number, sampleRate: number, padding: number) => {
return Math.floor((144 * bitrate / sampleRate) + padding);
export const computeMp3FrameSize = (layer: number, bitrate: number, sampleRate: number, padding: number) => {
if (layer === 3) {
// Layer 1
return Math.floor((12 * bitrate / sampleRate + padding) * 4);
} else {
return Math.floor((144 * bitrate / sampleRate) + padding);
}
};
export const getXingOffset = (mpegVersionId: number, channel: number) => {
@@ -102,7 +107,7 @@ export const readFrameHeader = (word: number, reader: { pos: number; fileSize: n
return null;
}
const frameLength = computeMp3FrameSize(bitrate, sampleRate, padding);
const frameLength = computeMp3FrameSize(layer, bitrate, sampleRate, padding);
if (reader.fileSize !== null && reader.fileSize - startPos < frameLength) {
// The frame doesn't fit into the rest of the file
src/mp3/mp3-writer.ts
+2 -2
View File
@@ -56,7 +56,7 @@ export class Mp3Writer {
// Let's find the lowest bitrate for which the frame size is sufficiently large to fit all the data
const bitrateIndex = bitrates.findIndex((kbr) => {
return computeMp3FrameSize(1000 * kbr, sampleRate, padding) >= neededBytes;
return computeMp3FrameSize(data.layer, 1000 * kbr, sampleRate, padding) >= neededBytes;
});
if (bitrateIndex === -1) {
throw new Error('No suitable bitrate found.');
@@ -98,7 +98,7 @@ export class Mp3Writer {
this.writeU32(data.fileSize ?? 0);
this.writer.write(data.toc ?? new Uint8Array(100));
const frameSize = computeMp3FrameSize(1000 * bitrates[bitrateIndex]!, sampleRate, padding);
const frameSize = computeMp3FrameSize(data.layer, 1000 * bitrates[bitrateIndex]!, sampleRate, padding);
this.writer.seek(startPos + frameSize);
}
}