I am currently trying to create a simple conversion from (Hanyu) Pinyin to IPA for the Standard Mandarin pronunciation Pinyin was created for.

This conversion will be build on a table based mapping from Pinyin to IPA syllables and has some simple routines for coping with tone sandhi occurrences (see German Wikipedia on Mandarin tonsandhi).

Apart from the tonal aspect, conversion of plain syllables is pretty much straightforward. Based on the initial/final structure of Mandarin syllables (see earlier post on Views on initials and finals of Mandarin in Pinyin) one can create a mapping to IPA with only a few rules: while for duan and tuan the final part uan is the same, this is not that obvious for wen and dun. In the latter case one has to note that wen is the form uen, where an initial u will change to a w, and dun is the shortend form of what should actually be duen. A set of rules will make sure these "writing variations" in Pinyin will be taken care of, such that finally only a mapping from initials and finals needs to be done.

There are different works on IPA for the Mandarin language (I collect them here, additionally see the Wikipedias) and as pronunciation is highly dependant on the region (i.d. dialect), speaker (i.d. individual variation) and basically the fact that IPA seems to give you some freedom when choosing phonological descriptions, no proposition on a syllable set seems to come to the same solution.

For me it was important to have a set I could give a source for, so I checked my few books on this:

• Hànyǔ Pǔtōnghuà Yǔyīn Biànzhèng (汉语普通话语音辨正). Page 15, Běijīng Yǔyán Dàxué Chūbǎnshè (北京语言大学出版社), Beijing 2003, ISBN 7-5619-0622-6. - This is a book for learners of Mandarin Chinese. With the pronunciation it gives a set of training lessons.
• Das neue chinesisch-deutsche Wörterbuch - 新汉德词典, Shāngwù Yìnshūguǎn (商务印书馆), Beijing 2003, ISBN 7-100-00096-3. - This Chinese-German dictionary includes a table on pronunciation of Pinyin in IPA.

Both have nearly the same way of using IPA:

1. Aspiration is given using an apostrophe, though it seems [ʰ] is the standard character for this.
2. d and t ([t]), b and p ([p]), g and k ([k]), z and c ([ts]), zh and ch ([tʂ]), j and q ([tɕ]) use the same string except the latter ones including the [‘] to mark the aspiration.
3. For final vowels an a is an [a], an o can mostly be [o] or turn to [u], e can have several forms depending on the context (e.g. single vowel, diphthong...), u is mostly [u].

Differences in the usage of IPA:

1. Hànyǔ Pǔtōnghuà Yǔyīn Biànzhèng will use [ɤ] instead of [ə] for a single e vowel and it states a rule when this can change to a [ə]
2. ou is [ou] instead of [əu], uo is [uo] instead of [uə], ian is [iɛn] instead of [ian].
3. Das neue chinesisch-deutsche Wörterbuch has phones for initials y and w ([j] and [w]) whereas my first book places 有 under [iou] without mentioning any special phones.

Using this data a mapping should be easy to implement. What seems to be left is to implement the rule of sound changes for the final and single vowel e which Hànyǔ Pǔtōnghuà Yǔyīn Biànzhèng gives. Simply speaking it states that syllables like ge as in 哥哥 (older brother) will be pronounced differently depending on the tone, i.e. [kɤkə].

Addendum:In Mandarin phonology with IPA (2) I point out two issues in the two sources I believe to be errors.