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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"`Wave_write` does not write `pad byte`","articleBody":"# Bug report\n\n### Bug description:\n\n```python\nimport io\nimport wave\n\ntest_bytes = b\"RIFF&\\x00\\x00\\x00WAVEfmt \\x10\\x00\\x00\\x00\\x01\\x00\\x01\\x00\\x80\\xbb\\x00\\x00\\x80\\xbb\\x00\\x00\\x01\\x00\\x08\\x00data\\x01\\x00\\x00\\x00\\x80\\x00\"\n\nr = io.BytesIO(test_bytes)\n\nwith wave.open(r, mode=\"rb\") as rw:\n    nframes = rw.getnframes()\n    sampwidth = rw.getsampwidth()\n    nchannels = rw.getnchannels()\n    framerate = rw.getframerate()\n    frames = rw.readframes(-1)\n\nassert nframes == 1\nassert sampwidth == 1\nassert nchannels == 1\nassert frames == b\"\\x80\"\n\nw = io.BytesIO()\n\nwith wave.open(w, mode=\"wb\") as ww:\n    ww.setsampwidth(sampwidth)\n    ww.setnchannels(nchannels)\n    ww.setframerate(framerate)\n    ww.writeframes(frames)\n\nvalue = w.getvalue()\n\n# b'RIFF%\\x00\\x00\\x00WAVEfmt \\x10\\x00\\x00\\x00\\x01\\x00\\x01\\x00\\x80\\xbb\\x00\\x00\\x80\\xbb\\x00\\x00\\x01\\x00\\x08\\x00data\\x01\\x00\\x00\\x00\\x80'\nprint(value)\n\n# AssertionError\nassert test_bytes == value\nassert test_bytes[-1] == value[-1] == 0\nassert (\n    int.from_bytes(test_bytes[4:8], byteorder=\"little\")\n    == int.from_bytes(value[4:8], byteorder=\"little\")\n    == 38\n)\n```\n\nThe data written is missing the last pad byte`\\x00`.\nAlong with this, the size of the RIFF chunk is also incorrect.\n\nref: https://www.tactilemedia.com/info/MCI_Control_Info.html\n> If the chunk size is an odd number of bytes, a pad byte with value zero is written after ckData.\n\n### CPython versions tested on:\n\n3.12\n\n### Operating systems tested on:\n\nWindows\n\n\u003c!-- gh-linked-prs -->\n### Linked PRs\n* gh-145237\n\u003c!-- /gh-linked-prs -->\n","author":{"url":"https://github.com/sabonerune","@type":"Person","name":"sabonerune"},"datePublished":"2024-04-10T16:50:17Z","url":"https://github.com/python/cpython/issues/117716"}