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const { promisifyProcess } = require('./general-util')
const { spawn } = require('child_process')
// Some probers are sorta inconsistent; this function lets them try again if
// they fail the first time.
const tryAgain = function(times, func) {
return async function(...args) {
let n = 0
let ret
while (!ret && n < times) {
try {
ret = await func(...args)
} catch (error) {
if (n + 1 === times) {
throw error
}
}
n++
}
return ret
}
}
const metadataReaders = {
ffprobe: tryAgain(6, async filePath => {
const ffprobe = spawn('ffprobe', [
'-print_format', 'json',
'-show_entries', 'stream=codec_name:format',
'-select_streams', 'a:0',
'-v', 'quiet',
filePath
])
let probeDataString = ''
ffprobe.stdout.on('data', data => {
probeDataString += data
})
await promisifyProcess(ffprobe, false)
let data
try {
data = JSON.parse(probeDataString)
} catch (error) {
return null
}
if (typeof data !== 'object' || typeof data.format !== 'object') {
return null
}
return {
duration: parseFloat(data.format.duration),
fileSize: parseInt(data.format.size),
bitrate: parseInt(data.format.bit_rate)
}
}),
getMetadataReaderFor: arg => {
return metadataReaders.ffprobe
}
}
module.exports = metadataReaders
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