Emotion tags on Paxa TTS Flash (v1)

An emotion tag is a word in square brackets, written into the text of POST /v1/tts, that changes how a voice delivers what follows it. The delivery changes at the tag and holds until the next tag. Text before the first tag keeps the voice's own delivery. The experimental voices Khanom Chan and Kaprao read tags. Every other v1 voice skips them, and every Paxa TTS Flash v2 voice reads direction tags instead.

GET /v1/voices lists the tags each voice reads in emotion_tags, empty for a voice that skips them, and marks these voices experimental: true. An experimental voice keeps its id, and its delivery can change while we tune it.

The voices above read these words, each written before the text it should color: [neutral], [calm], [normal], [plain], [happy], [excited], [cheerful], [joyful], [amazed], [laughing], [sad], [crying], [sorrowful], [gloomy], [disappointed], [angry], [shouting], [furious], [annoyed], [frustrated], [afraid], [scared], [fearful], [nervous], [terrified], [anxious].

• Case is ignored, and _ and - read as spaces: [Sad] and [sad_] are both [sad].
• A bracketed word outside the tag list, such as [laughs], answers 400 tag_invalid.
• Brackets that do not hold a word, such as [1] or [ไทย], are text and are spoken. A word outside the list followed by a colon, such as [Fig:2] or [note: see below], is text too.
• Text that holds only tags answers 422 unspeakable_text before anything is charged.

A weight after a colon sets how strongly the tag applies, from 0 to 1, as in [sad:0.5]. Write it as a number from 0 to 1 or as a percentage, such as [sad:.25], [sad:0,5], or [sad:50%]. The API reads it to the thousandth, and a value past either end reads as that end: [angry:1.5] is [angry]. A tag at weight 0 does not apply. A weight that is not a number, such as [sad:half], answers tag_invalid.

Tags are text. Every character of a tag counts toward the request's length and its charge, at the model's per-character rate. The 81-character example above, tags included, costs 0.81 credits. Credits and billing covers rounding and the minimum.

A v1 voice that reads no tags skips every tag on the list, whatever its weight, and reads the rest of the text. It refuses nothing. On those voices a bracketed word outside the list, such as [laughs], is text and is spoken. The characters of a skipped tag still count toward the charge.

On a live connection a text frame whose tag the voice cannot read answers an error event with tag_invalid, and the buffer keeps the text it held before the frame. Auto-flush holds back a tag still open at the end of the buffer, and a tag split across frames is read whole. One still open past the length threshold that flushes untagged text is read as text and is not checked as a tag. Tags that no words follow yet wait in the buffer for them. Each synthesis leg opens in the delivery the previous leg ended in. Those opening tags carry no charge. They count toward max_chars and may fill at most half of it. A frame that would leave longer opening tags, or take the tags waiting in the buffer and the opening tags past max_chars, answers text_too_long. cancel returns the connection to the voice's own delivery.