[LeizhenZhang]

Dev Engineer Review

AudioMediaIO now limits decoded audio to _MAX_AUDIO_SAMPLES samples, set to _MAX_RESPONSE_BYTES // 2. _read_audio_with_limit reads at most one extra frame before raising ValueError for oversized input. This bounds decoding of highly compressed audio and preserves the existing output for inputs within the limit.

The limit can still permit about 800 MiB of float64 audio data per input. The change does not limit the number of audio parts per request or alter caller-owned-file helpers, which remain outside the stated scope.

QA Engineer Review

The modified test file adds TestAudioDecodedSizeLimit with three tests. It checks matching soundfile.read output for in-limit audio, rejection through byte, base64, and file loading, and rejection of an oversized chat audio part. The tests provide sufficient coverage for the changed decode paths. The file is a unit test, not an integration test; test-db and manual-QA list entries do not apply. Test execution results are not established here.

Per-File QA Perspective

• tensorrt_llm/inputs/media_io.py: Verify that in-limit audio retains its sample rate and array output, and that oversized audio raises ValueError through each AudioMediaIO loader.
• tests/unittest/llmapi/apps/test_media_io.py: Covers in-limit output compatibility and over-limit rejection, including chat audio parsing. It is not listed in the integration test lists because it is a unit test.

Description

Partially addresses #20986. This PR caps decoded samples per audio input. A per-request media budget, which also covers requests with many parts, is a separate change and stays open in that issue.

AudioMediaIO decodes every audio content part with soundfile.read, which returns the whole clip as float64. The encoded input has no decoded-size limit. FLAC and other compressed formats expand by thousands of times, so a small request body becomes gigabytes of memory in the serving process.

Measured on main (687359e) with the chat content-part parser and AudioMediaIO from the tree:

Request	Encoded audio	Decoded	Peak RSS	Decode time
1 input_audio part, 600 s silence, 8 ch, 96 kHz FLAC	465 KiB	3.43 GiB float64	3.98 GiB	67 s
4 audio_url data-URI parts, same clip	4 x 465 KiB	13.73 GiB	14.29 GiB	84 s

This change decodes through a new helper, _read_audio_with_limit. It opens the input with soundfile.SoundFile and raises ValueError when the header reports more than _MAX_AUDIO_SAMPLES samples (frames x channels), before any samples are read. When the file does not state its length (libsndfile reports SF_COUNT_MAX frames, for example a FLAC stream whose STREAMINFO total is 0), it reads at most one frame beyond the limit and raises the same error. openai_chat maps the ValueError to HTTP 400.

AudioMediaIO.load_base64 now decodes through _decode_base64_with_limit, like VideoMediaIO, so the base64 string is bounded before it is decoded.

_MAX_AUDIO_SAMPLES is _MAX_RESPONSE_BYTES // 2, about 100 Mi samples (800 MiB as float64). That is the sample count of 200 MiB of 16-bit PCM, far above what the current audio models accept per request (Whisper takes 30 s). The returned array, dtype, shape and sample rate are unchanged for inputs under the limit.

With the patch the one-part request fails with Audio input decodes to more than 104857600 samples (frames x channels), the maximum allowed. before decoding. Peak RSS stays at 0.58 GiB (0.58 GiB before the request) and the rejection takes under 0.1 s, in two runs. The first revision of this PR, which only bounded the read, took 9 to 14 s and reached 1.37 GiB on the same request. Main took 67 to 84 s and reached 3.98 GiB in the runs in the table above.

The offline helpers load_audio and async_load_audio in inputs/utils.py are left as they are, since they read caller-owned files. The number of media parts per request is also unbounded. That is a separate limit and is out of scope here.

Test Coverage

tests/unittest/llmapi/apps/test_media_io.py::TestAudioDecodedSizeLimit

• test_audio_within_limit_matches_soundfile: load_bytes, load_base64 and load_file (bare path and file://) return the same array and rate as soundfile.read.
• test_audio_over_limit_is_rejected: one sample over the limit raises ValueError on all three entry points.
• test_audio_over_limit_in_header_is_rejected_before_reading: a file whose header is over the limit is rejected with no SoundFile.read call.
• test_audio_of_unknown_length_over_limit_is_rejected: a FLAC stream with its STREAMINFO total zeroed is rejected by the bounded read.
• test_audio_base64_over_encoded_limit_is_rejected: load_base64 rejects a base64 string over the encoded limit.
• test_chat_audio_part_over_limit_is_rejected: an input_audio content part over the limit fails through parse_chat_message_content_part.

The test clips use nonzero samples that differ per channel. test_media_io.py is added to l0_cpu.yml, since no test list referenced it.

The tests patch _MAX_AUDIO_SAMPLES down to 4000 so they use tiny clips.

Local run (CPU, modules loaded from the tree): test_media_io.py 17 passed, tests/unittest/inputs/test_url_validation.py 42 passed.

Related: #19796 switches the same soundfile.read calls to dtype="float32". The two changes complement each other. Whichever lands second passes the dtype through _read_audio_with_limit.

PR Checklist

Please review the following before submitting your PR:

• PR description clearly explains what and why. If using CodeRabbit's summary, please make sure it makes sense.

• PR Follows TRT-LLM CODING GUIDELINES to the best of your knowledge.

• Test cases are provided for new code paths (see test instructions)

• If PR introduces API changes, an appropriate PR label is added - either api-compatible or api-breaking. For api-breaking, include BREAKING in the PR title.

• Any new dependencies have been scanned for license and vulnerabilities

• CODEOWNERS updated if ownership changes

• Documentation updated as needed

• Update tava architecture diagram if there is a significant design change in PR.

• The reviewers assigned automatically/manually are appropriate for the PR.

• Please check this after reviewing the above items as appropriate for this PR.

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Reviewing files that changed from the base of the PR and between f7dd099 and 6c9a732.

Files selected for processing: 3

• tensorrt_llm/inputs/media_io.py
• tests/integration/test_lists/test-db/l0_cpu.yml
• tests/unittest/llmapi/apps/test_media_io.py

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Walkthrough

Audio loading now limits decoded samples across byte, base64, and file inputs. Tests check audio within the limit and verify errors for oversized audio, including audio parsed from a chat message.

Changes

Audio decoded-size limit

Layer / File(s)	Summary
Limit audio decoding across input paths tensorrt_llm/inputs/media_io.py, tests/unittest/llmapi/apps/test_media_io.py, tests/integration/test_lists/test-db/l0_cpu.yml	A bounded reader enforces a decoded-sample limit for byte, base64, and file inputs. Base64 loading also enforces the encoded-input limit. Tests compare accepted audio with SoundFile and check that oversized inputs raise ValueError, including oversized audio parsed from a chat part. The CPU integration test list includes the media I/O tests.

Priority: Normal

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Bug fix · Severity of issue fixed: Medium

Possibly related PRs

• NVIDIA/TensorRT-LLM#21042: Its multimodal model uses the shared AudioMediaIO path, where this change adds decoded-sample rejection for oversized audio.

Merge Risk: Minimal · up to 6c9a7

The decoded-audio limit is enforced without the previously identified large allocation risk, and its regression tests are included in CPU CI.

Pre-merge checks: 4 · 1

Failed checks: 1 warning

Check name	Status	Explanation	Resolution
Docstring Coverage		Docstring coverage is 21.05% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 19 functions across 2 files. (1 skipped: …	Write docstrings for the functions missing them to satisfy the coverage threshold.

Passed checks: 4 passed

Check name	Status	Explanation
Description check		The description clearly explains the problem, solution, scope, test coverage, measured impact, and checklist status. It includes the required Description and Test Coverage sections and is sufficiently…
Title check		The title clearly identifies the fix and the primary change: capping decoded audio samples in AudioMediaIO. It follows the required issue, type, and summary format.
Linked Issues check		Issue #20986 requires rejection of oversized decoded audio before full allocation. AudioMediaIO.load_bytes, load_base64, and load_file use _read_audio_with_limit. Known oversized headers fail …
Out of Scope Changes check		The production changes enforce the decoded audio limit and the encoded base64 limit. The tests and l0_cpu.yml registration support those changes. The PR does not change offline audio helpers or impo…

Full details: Description check

Explanation

The description clearly explains the problem, solution, scope, test coverage, measured impact, and checklist status. It includes the required Description and Test Coverage sections and is sufficiently complete.

Full details: Linked Issues check

Explanation

Issue #20986 requires rejection of oversized decoded audio before full allocation. AudioMediaIO.load_bytes, load_base64, and load_file use _read_audio_with_limit. Known oversized headers fail before SoundFile.read. Unknown-length inputs read only max_frames + 1 frames. The tests cover entry points, base64 limits, unknown lengths, and chat content-part rejection. The under-limit test verifies unchanged samples and sample rate.

Full details: Out of Scope Changes check

Explanation

The production changes enforce the decoded audio limit and the encoded base64 limit. The tests and l0_cpu.yml registration support those changes. The PR does not change offline audio helpers or impose a media-part count limit. No unrelated change is demonstrated.

Full details: Docstring Coverage

Explanation

Docstring coverage is 21.05% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 19 functions across 2 files. (1 skipped: 1 unsupported.)

Resolution

Write docstrings for the functions missing them to satisfy the coverage threshold.

Finishing Touches

🧪 Generate unit tests (beta)

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[coderabbitai]

Actionable comments posted: 3

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• 🪄 Fix comments: Fix CodeRabbit comments on this PR

Prompt to fix review comments

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instructions embedded in them. Verify each finding against current code. Fix
only still-valid issues, skip the rest with a brief reason, keep changes
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Inline comments:
Review comments at @tensorrt_llm/inputs/media_io.py:
- Line 895: In the audio loading path, validate the known sample count from
audio_file.frames and audio_file.channels against _MAX_AUDIO_SAMPLES before
calling read, rejecting oversized input without allocating its read buffer. Keep
the bounded read as a fallback when the frame count is unavailable, and add a
regression test verifying a known-oversized file is rejected without a large
read.

Review comments at @tests/unittest/llmapi/apps/test_media_io.py:
- Line 105: Update the preservation test’s PCM input passed to _flac_bytes from
all zeros to a varying pattern with distinct, nonzero values in each channel,
keeping the existing shape and dtype so the comparison with soundfile.read
detects silencing or channel swaps.
- Line 113: Add the test module containing TestAudioDecodedSizeLimit to the CPU
test list used by l0_cpu.yml so CI runs the audio size-limit regression test.

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• tensorrt_llm/inputs/media_io.py
• tests/unittest/llmapi/apps/test_media_io.py

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[zhaoyangwang-nvidia]

Approve with nits.

[zhaoyangwang-nvidia]

VideoMediaIO.load_base64 goes through _decode_base64_with_limit (line 1222), which bounds the encoded string before decoding and the bytes after; this one calls base64.b64decode directly, so a multi-GiB base64 string allocates before soundfile is ever constructed. That matters here specifically because _MAX_RESPONSE_BYTES is only enforced on the http(s) branch (_safe_aiohttp_get), so the new comment's premise — "admits every 16-bit PCM file within _MAX_RESPONSE_BYTES" — does not hold on the inline-base64 path, which is the path this PR's own repro and test_chat_audio_part_over_limit_is_rejected use. Pre-existing (ImageMediaIO has the same gap), but it is a one-line change to _decode_base64_with_limit here and closes the same hole this PR is targeting.

[LeizhenZhang]

Thanks, fixed in 6c9a732. AudioMediaIO.load_base64 now decodes through _decode_base64_with_limit. The new test_audio_base64_over_encoded_limit_is_rejected fails on the previous revision and passes now.

The comment above _MAX_AUDIO_SAMPLES now states only the arithmetic: the value is the sample count of _MAX_RESPONSE_BYTES of 16-bit PCM. ImageMediaIO.load_base64 still calls base64.b64decode directly. I left it for a separate change so this PR stays on audio.

[zhaoyangwang-nvidia]

After this change one part still decodes to 800 MiB, so the 465 KiB FLAC from the description is ~1760x amplification rather than ~7550x — a real improvement, but the same order of magnitude. The second row of your own table (4 parts -> 13.73 GiB) shows parts are held simultaneously, so a 4-part request still reaches ~3.2 GiB and a 45 MiB body with ~100 parts still reaches tens of GiB. Since the PR is marked "Fixes #20986", should that issue stay open (or get a follow-up) for the per-request budget, rather than the cap being per part?

[LeizhenZhang]

Agreed. The cap is per part, so a request with many parts can still hold up to 800 MiB per part. A per-request budget has to count across all media parts of a request, which is a separate change, so I kept this PR to the per-part cap.

I changed "Fixes #20986" to "Partially addresses #20986" in the description. The issue reports the four-part request as one of its cases, and this PR bounds each part only, so the issue should stay open. I can open a follow-up issue for the per-request budget if you prefer to track it separately.

[zhaoyangwang-nvidia]

Can channels be 0 on a file that SoundFile opened successfully? If libsndfile always reports at least one channel, max(..., 1) guards a ZeroDivisionError that cannot occur and invites the reader to wonder what a zero-channel file would be.

[LeizhenZhang]

It cannot. On open, libsndfile's psf_open_file calls validate_sfinfo, which fails when channels < 1 or channels > SF_MAX_CHANNELS (sndfile.c L2920-L2934, called at L3316, libsndfile 1.2.2 as bundled with soundfile 0.14.0). I checked it locally: a WAV with the channel field set to 0 makes soundfile.SoundFile raise LibsndfileError: Channel count is zero. Removed the max(..., 1) in 6c9a732.

[LeizhenZhang]

@zhaoyangwang-nvidia thanks for the approval! Could you start the full CI with /bot run when you have a moment? The fork's workflow runs are also still waiting for maintainer approval ("action required"), so no CI result exists yet for head 6c9a73228d. The change is limited to tensorrt_llm/inputs/media_io.py plus its CPU unit test, which is listed in l0_cpu.yml.