[FFmpeg-user] Ingest of SMPTE-377M

Mark Nelson markn at ieee.org
Sat Dec 26 19:03:32 CET 2015

>Please provide such a sample

Thanks Carl!

This file is a raw AC-3 sample:


This file has the same data after being packetized into SMPTE-377M and
placed in a WAV file suitable for playout on an SDI card at 1536 kbps:


Most apps that can handle WAV files will get garbage when reading this -
scratchy nonsense. But ffmpeg knows better, and some apps like MediaInfo
see through it:

Format                                   : AC-3
Format/Info                              : Audio Coding 3
Mode                                     : 16
Mode extension                           : CM (complete main)
Format settings, Endianness              : Little
Muxing mode                              : AES3
Codec ID                                 : 1

Anyway, the desire is to be able to force ffmpeg to treat this at face
value: stereo PCM at 1536 kbps - at least when desired.

The SMPTE-337 headers normally start with 72 f8 1f 4e xx xx xx xx followed
by a payload.

The payload always starts with a dolby header, first two bytes 77 0b.


Mark Nelson – markn at ieee.org - http://marknelson.us

On Fri, Dec 25, 2015 at 4:27 AM, Carl Eugen Hoyos <cehoyos at ag.or.at> wrote:

> Mark Nelson <markn <at> ieee.org> writes:
> > Oddly, it does not do this when the stream is eac3,
> > but that is a different issue.
> Please provide such a sample.
> I'll probably work on a patch for your issue
> next week.
> Merry Christmas, Carl Eugen
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