Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add damionrashford/media-os --skill ffmpeg-bitstreamgit clone --depth 1 https://github.com/damionrashford/media-osWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/damionrashford/media-os/ffmpeg-bitstream)<a href="https://agentmods.dev/skills/damionrashford/media-os/ffmpeg-bitstream"><img src="https://agentmods.dev/badge/skills/damionrashford/media-os/ffmpeg-bitstream/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/damionrashford/media-os/ffmpeg-bitstream"><img src="https://agentmods.dev/badge/skills/damionrashford/media-os/ffmpeg-bitstream.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00146 | $0.05215 |
| Opus 5 | $0.00073 | $0.02608 |
| Sonnet 5 | $0.00029 | $0.01043 |
| Haiku 4.5 | $0.00015 | $0.00522 |
Grade A, and why
ffmpeg-bitstream scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 10d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 405 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Ffmpeg Bitstream
Context: $ARGUMENTS
Quick start
- MP4 H.264 → TS/HLS:
-bsf:v h264_mp4toannexb→ Step 3, recipe A - MP4 HEVC → TS:
-bsf:v hevc_mp4toannexb→ Step 3, recipe A - TS AAC → MP4:
-bsf:a aac_adtstoasc→ Step 3, recipe B - Old DivX/XviD packed B-frames:
-bsf:v mpeg4_unpack_bframes→ Step 3, recipe D - Rewrite H.264 level / VUI:
-bsf:v h264_metadata=...→ Step 3, recipe E - Strip SEI / AUD / filler NALs:
-bsf:v filter_units=remove_types=6→ Step 3, recipe F - Dump extradata into every keyframe (streaming recovery):
-bsf:v dump_extra=freq=k - Zero-base timestamps without re-encoding:
-bsf:v setts=ts=PTS-STARTPTS - Debug NAL/SPS/PPS structure:
-bsf:v trace_headers
When to use
- Container mux fails with
Malformed AAC bitstream detected/H.264 bitstream not in Annex-B format. - Need to remux MP4 ↔ TS / HLS / MKV with
-c copy(no re-encode, no quality loss). - Change H.264/HEVC level, profile, color primaries, or VUI flags without touching pixels.
- Split a stream into segments that need keyframe-carried SPS/PPS for mid-stream joins.
- Strip SEI/AUD NAL units a downstream decoder chokes on.
- Rewrite PTS/DTS on the packet level (e.g. zero-base timestamps, offset by N).
- Pull SPS/PPS out of a file for a hardware pipeline.
- Fix broken old MP4s with packed B-frames (DivX/XviD era).
- For re-encode workflows use
ffmpeg-transcode; for trimming useffmpeg-cut-concat; for pure container inspection useffmpeg-probe.
Step 1 — Identify the mux / codec mismatch
Probe first — bsf choice depends on codec + source container + target container:
ffprobe -v error -show_entries stream=index,codec_type,codec_name,profile -of json "$IN"
What to look at:
- Video
codec_name=h264→ pickh264_mp4toannexborh264_metadata. - Video
codec_name=hevc/h265→ pickhevc_mp4toannexborhevc_metadata. - Audio
codec_name=aaccoming frommpegts→ needaac_adtstoascfor MP4. - Source container =
.mp4/.mov(AVCC / length-prefixed NAL) vs.ts/.flv(Annex-B / start-code NAL) — this is the framing that bsf rewrites.
What ships with it
2 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 10d ago First seen · 405 lines · 146 tokens per session scan A cc81c7682a23
ffmpeg-bitstream is a skill published in the GitHub repository damionrashford/media-os (18 stars, last pushed 3mo ago), licensed MIT. It adds 146 tokens to every session and 5,215 once invoked, about $0.0007 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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