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| 1 | sleepysaint's guide to adam to get into what.cd without invite | |
| 2 | ||
| 3 | begging: | |
| 4 | ||
| 5 | I got a list of possible interview questions from some forums. My | |
| 6 | ||
| 7 | questions were a little different than these both times but I got | |
| 8 | ||
| 9 | some of the same ones. I went through and detailed the correct | |
| 10 | ||
| 11 | answers to each of these. You'd do well to study on formats but I | |
| 12 | ||
| 13 | hope I've done the grunt work for you. | |
| 14 | The bottom line is, they want to know that you understand what | |
| 15 | ||
| 16 | transcoding is in all circumstances because they're really | |
| 17 | ||
| 18 | intolerance of bad transcodes and lossy music. As such, you should | |
| 19 | ||
| 20 | first be familiar with lossy and lossless audio formats. | |
| 21 | Allowed on what.cd: | |
| 22 | Lossless: FLAC, DTS (don't worry about DTS) | |
| 23 | Lossy: MP3 at 192kb/s or GREATER. no less. Ogg. AAC. AC3. (don't | |
| 24 | ||
| 25 | worry about AC3) | |
| 26 | They'll probably ask you about formats not allowed on what too. | |
| 27 | Lossless: FLAC, ALAC, APE, WAV(PCM), WMV, CDDA (CD audio) | |
| 28 | ||
| 29 | Read about each of these formats on wiki. Some are container formats, | |
| 30 | ||
| 31 | meaning they could contain various types of audio data. | |
| 32 | ||
| 33 | http://wiki.hydrogenaudio.org/index.php? | |
| 34 | ||
| 35 | title=LAME#Detailed_explanation_.28long_answer.29 | |
| 36 | ||
| 37 | That's your cheat sheet for MP3 bit rates. | |
| 38 | The hydrogenaudio wiki has a lot of info on other things as well, so | |
| 39 | ||
| 40 | read up. | |
| 41 | ||
| 42 | **The sample questions follow. They might ask you a totally different | |
| 43 | ||
| 44 | set of questions about different things, like putting formats in | |
| 45 | ||
| 46 | order or who knows what. You can cheat and google or use whatever | |
| 47 | ||
| 48 | resources you have handy to find the answer but it's a timed test so | |
| 49 | ||
| 50 | you gotta be quick. These are here to show you a lot of repetitive | |
| 51 | ||
| 52 | answers that should come quickly. The overarching point is Lossless- | |
| 53 | ||
| 54 | >lossy = good and lossy->anything = BAD. | |
| 55 | ||
| 56 | ||
| 57 | They're gonna ask you some preliminary questions, probably something | |
| 58 | ||
| 59 | along the lines of the following: | |
| 60 | ||
| 61 | 1. Why are you interested in becoming a What member? | |
| 62 | Because you like obscure music and you're interested in knowing the | |
| 63 | ||
| 64 | quality of the music you get, right? Mention liking FLAC and lossless | |
| 65 | ||
| 66 | music for bonus points | |
| 67 | ||
| 68 | 2. How often do you plan on using the site? | |
| 69 | Tell the truth, if you're like me you'll use it all the time. | |
| 70 | ||
| 71 | 3. What kind of internet connection do you have? | |
| 72 | They're gonna ask you before the interview to do a speedtest at | |
| 73 | ||
| 74 | speedtest.net and send them a link to the screenshot. if you normally | |
| 75 | ||
| 76 | run on wireless you might wanna wire into the wall when you do this, | |
| 77 | ||
| 78 | just to improve ping. they'll accept it no matter what. just tell the | |
| 79 | ||
| 80 | truth. | |
| 81 | ||
| 82 | 4. Are you a member of any other private trackers? | |
| 83 | Have a screenshot of your demonoid stats and username uploaded | |
| 84 | ||
| 85 | somewhere, link them. | |
| 86 | ||
| 87 | 5. How much experience do you have creating & uploading torrents? | |
| 88 | ||
| 89 | Which BT client do you use? | |
| 90 | Tell them the truth. | |
| 91 | ||
| 92 | 7. How big is your music/cd collection? What bitrates/formats? Where | |
| 93 | ||
| 94 | did you get your collection (internet-where?/own rips-read ahead) | |
| 95 | Tell them the truth. | |
| 96 | ||
| 97 | 8. What application do you usually use to rip CDs & how many you have | |
| 98 | ||
| 99 | (estimate)? | |
| 100 | Tell them you use Exact Audio Copy to rip CDs and if you've never | |
| 101 | ||
| 102 | used it before then tell them that's what you plan to use. | |
| 103 | ||
| 104 | 9. What is the difference between a lossy & a lossless audio codec? | |
| 105 | A lossless audio codec preserves all of the auditory information from | |
| 106 | ||
| 107 | the source data. A lossy codec irretrievably loses some of the | |
| 108 | ||
| 109 | auditory data due to compression, resulting in a lower quality sound | |
| 110 | ||
| 111 | but a smaller file size. | |
| 112 | ||
| 113 | 10. What are VBR & CBR? Out of following pick the highest standard | |
| 114 | ||
| 115 | LAME mp3 bitrate: 192, V0, V2, 320, V4, 512? | |
| 116 | In Constant Bit Rate encoding, the bitrate is kept constant across | |
| 117 | ||
| 118 | each sample of audio in the file. In Variable Bit Rate encoding, the | |
| 119 | ||
| 120 | encoder (for instance, LAME encoder for MP3s) chooses the number of | |
| 121 | ||
| 122 | bits per sample based on the auditory complexity. VBR typically | |
| 123 | ||
| 124 | results in more efficient filesizes if comparing equal sound quality | |
| 125 | ||
| 126 | between VBR and CBR. (if that last sentence is confusing ignore it) | |
| 127 | ||
| 128 | Out of that list, 320CBR is the highest *standard* lame preset for | |
| 129 | ||
| 130 | quality, because 512 isn't a LAME standard. | |
| 131 | ||
| 132 | 11. What is transcoding, in terms of audio? Transcoding is simply | |
| 133 | ||
| 134 | converting a digital audio file from one format to another via a | |
| 135 | ||
| 136 | codec. There are four types of transcodes that can happen between | |
| 137 | ||
| 138 | digital files: | |
| 139 | Lossless to lossless | |
| 140 | Lossless to lossy | |
| 141 | Lossy to Lossless | |
| 142 | Lossy to Lossy | |
| 143 | ||
| 144 | Of those, only the first two are allowed on what.cd, as the others | |
| 145 | ||
| 146 | are considered "lossy transcodes". | |
| 147 | ||
| 148 | 12. Will these transcodes give the same result as if they were done | |
| 149 | ||
| 150 | straight from an original cd? "YES" or "NO" for each one please. | |
| 151 | a. 320 -> 192 no | |
| 152 | b. V2 -> 192 no | |
| 153 | c. 256 -> 256 no | |
| 154 | d. 256 -> 320 no | |
| 155 | e. wma -> mp3 yes | |
| 156 | f. FLAC -> mp3 yes | |
| 157 | g. mp3 -> Audio CD -> mp3 no | |
| 158 | h. mp3 -> Audio CD -> FLAC no | |
| 159 | ||
| 160 | The only time it will give the same result as if it came directly | |
| 161 | ||
| 162 | from a CD is if it's a lossless format transcoded to something else. | |
| 163 | ||
| 164 | ANY TIME you convert from one kind of mp3 to another, it's a bad | |
| 165 | ||
| 166 | transcode. ANY TIME you burn a CD from mp3s and rerip it, it's a bad | |
| 167 | ||
| 168 | transcode. | |
| 169 | ||
| 170 | If no more than one lossless to lossy encoding is permitted which of | |
| 171 | ||
| 172 | these transcodes are/is generally acceptable? Give only a YES or NO | |
| 173 | ||
| 174 | for each specified example. | |
| 175 | a. CDDA->WAV->CBR yes (WAV is lossless) | |
| 176 | b. 320->WAV(PCM)->FLAC no (source 320 is lossy) | |
| 177 | c. MP3->WMA->AAC no (source MP3 is lossy) | |
| 178 | d. AAC->MP3->ALAC no (middle MP3->ALAC is lossy->lossless) | |
| 179 | e. FLAC->APE->WAV(PCM) yes (all three are lossless) | |
| 180 | f. APE->FLAC->APE yes (same as above) | |
| 181 | g. FLAC->WAV(PCM)->CDDA yes (all three are lossless) | |
| 182 | h. WAV(PCM)->ALAC->AAC yes (Lossless->lossless->lossy) | |
| 183 | i. MP3->APE->FLAC no (source mp3 is lossy) | |
| 184 | j. V0->CBR->WAV(PCM) no (two no-nos here) | |
| 185 | k. CDDA->WAV(PCM)->MP3 yes | |
| 186 | l. V2->V1->V3 no | |
| 187 | m. V0->WAV(PCM)->CDDA no | |
| 188 | ||
| 189 | I hope you get the idea? Remember these questions will be different. | |
| 190 | ||
| 191 | 2. Which conversions are acceptable without having *obvious* quality | |
| 192 | ||
| 193 | loss? No more than one (1) lossless to lossy transcode is allowed to | |
| 194 | ||
| 195 | take place. Answer Y (YES) or N (NO) to the following: | |
| 196 | ||
| 197 | a. 192 MP3 -> 320 MP3 N | |
| 198 | b. CDDA (CD) -> FLAC Y | |
| 199 | c. 320 MP3 -> 192 MP3 -> q6 Vorbis (Ogg) N | |
| 200 | d. FLAC -> CDDA (CD) -> 320 MP3 Y | |
| 201 | e. APE -> FLAC -> q7 Vorbis (Ogg) Y | |
| 202 | f. WAV (PCM) -> 256 MP3 -> APE -> FLAC N | |
| 203 | g. V0 MP3 -> CDDA (CD) -> 320 AAC (MPA/MP4) -> WAV Absolutely NOT | |
| 204 | h. ALAC (MPA/MP4) -> CDDA (CD) -> APE -> V2 MP3 -> FLAC no (the last | |
| 205 | ||
| 206 | two are lossy to lossless) | |
| 207 | ||
| 208 | got those from <@clockoutx> only got 5 right for this havn't changed | |
| 209 | ||
| 210 | them so again up to you to find out them | |
| 211 | ||
| 212 | 1. How often will you use the site? | |
| 213 | Be honest, I use it multiple times daily unlike any other music site | |
| 214 | ||
| 215 | I've ever been on including demonoid. | |
| 216 | ||
| 217 | 2. How long will you seed for daily, and how long in total? | |
| 218 | As long as you can, never stop seeding. | |
| 219 | ||
| 220 | 3. What is the concept of maintaing a ratio? | |
| 221 | You know this. | |
| 222 | ||
| 223 | 4. Will you be able to maintain an acceptable ratio on What.cd? Can | |
| 224 | ||
| 225 | you prove to me that you have been able to do this on other private | |
| 226 | ||
| 227 | bittorrent sites? | |
| 228 | You'll try your best by limiting your downloads until you've uploaded | |
| 229 | ||
| 230 | your fair share. | |
| 231 | ||
| 232 | 1. Explain how lossy and lossless audio codecs are different Give | |
| 233 | ||
| 234 | three examples of each. | |
| 235 | This is a repeat question. I'll repeat what I said above: A lossless | |
| 236 | ||
| 237 | audio codec preserves all of the auditory information from the source | |
| 238 | ||
| 239 | data. A lossy codec irretrievably loses some of the auditory data due | |
| 240 | ||
| 241 | to compression, resulting in a lower quality sound but a smaller file | |
| 242 | ||
| 243 | size. | |
| 244 | ||
| 245 | Lossy codec examples: AAC, Ogg vorbis, MP3 | |
| 246 | Lossless codec examples: FLAC, ALAC, APE | |
| 247 | ||
| 248 | 2. What is CBR & VBR? How are they different? Explain. | |
| 249 | Repeat answer: In Constant Bit Rate encoding, the bitrate is kept | |
| 250 | ||
| 251 | constant across each sample of audio in the file. In Variable Bit | |
| 252 | ||
| 253 | Rate encoding, the encoder (for instance, LAME encoder for MP3s) | |
| 254 | ||
| 255 | chooses the number of bits per sample based on the auditory | |
| 256 | ||
| 257 | complexity. VBR typically results in more efficient filesizes if | |
| 258 | ||
| 259 | comparing equal sound quality between VBR and CBR. (if that last | |
| 260 | ||
| 261 | sentence is confusing ignore it) | |
| 262 | ||
| 263 | 3. What is v0? | |
| 264 | V0 ("Preset Fast Extreme") is a VBR preset in the LAME mp3 encoder.
| |
| 265 | ||
| 266 | The target bit rate for V0 MP3 is 245kbit/s but obviously can vary. | |
| 267 | ||
| 268 | 4. What is the highest possible mp3 bitrate? | |
| 269 | 320kbit/s CBR is the highest possible using LAME encoder. | |
| 270 | ||
| 271 | 5. Give examples of methods that could be used to prove an audio file | |
| 272 | ||
| 273 | is actually the type of format/bitrate advertised. | |
| 274 | Using a program such as Audio Identifier will help, but one way that | |
| 275 | ||
| 276 | works well is looking at the frequency spectrogram of the audio file. | |
| 277 | ||
| 278 | If it has been transcoded from a lossy source, there should be | |
| 279 | ||
| 280 | telltale signs (a distinct pattern or line at a lower frequency than | |
| 281 | ||
| 282 | the claimed bitrate should cut off at). | |
| 283 | ||
| 284 | 6. - Define transcoding - In terms of audio. | |
| 285 | Is it good or bad and why? | |
| 286 | Are there good AND bad transcodes? Explain. | |
| 287 | Transcoding is just converting digital audio data from one form to | |
| 288 | ||
| 289 | another. Transcoding is good because it allows people to convert a | |
| 290 | ||
| 291 | very large lossless format into something compressed/more manageable. | |
| 292 | ||
| 293 | Without transcoding there would be no way to put your CD collection | |
| 294 | ||
| 295 | on your iPod. But there are bad ways of transcoding - that is, taking | |
| 296 | ||
| 297 | a lossy file such as an MP3 and transcoding it again. Since it has | |
| 298 | ||
| 299 | already been compressed in a lossy format, any more transcoding done | |
| 300 | ||
| 301 | to the file will result it a great loss of information and much | |
| 302 | ||
| 303 | poorer sound quality. A good transcode is one that comes from a | |
| 304 | ||
| 305 | lossless source, such as an original CD or a FLAC file. |