[FFmpeg-devel] [PATCH]lavf/matroskaenc: Print an error if an unreadable rawvideo pix_fmt is written

[Hendrik Leppkes]

On Sat, Jan 14, 2017 at 4:18 PM, Carl Eugen Hoyos <ceffmpeg at gmail.com> wrote:
> 2017-01-13 6:28 GMT+01:00 wm4 <nfxjfg at googlemail.com>:
>> On Thu, 12 Jan 2017 23:31:11 +0100
>> Carl Eugen Hoyos <ceffmpeg at gmail.com> wrote:
>>
>>> 2017-01-12 23:20 GMT+01:00 Hendrik Leppkes <h.leppkes at gmail.com>:
>>> > On Fri, Jan 13, 2017 at 1:10 AM, Carl Eugen Hoyos <ceffmpeg at gmail.com> wrote:
>>> >> 2017-01-11 12:24 GMT+01:00 Moritz Barsnick <barsnick at gmx.net>:
>>> >>> On Tue, Jan 10, 2017 at 17:05:47 +0100, Carl Eugen Hoyos wrote:
>>> >>>> +                enum AVPixelFormat pix_fmt = avpriv_find_pix_fmt(avpriv_pix_fmt_bps_avi,
>>> >>>> +                                                                 par->bits_per_coded_sample);
>>> >>>> +                if (par->format != pix_fmt && par->format != AV_PIX_FMT_NONE)
>>> >>>> +                    av_log(s, AV_LOG_ERROR, "%s rawvideo cannot be written to vfw mkv, output file will be unreadable\n",
>>> >>>> +                          av_get_pix_fmt_name(par->format));
>>> >>>
>>> >>> Should it really be an error (and not a warning) if its detection
>>> >>> doesn't change ffmpeg's behavior?
>>> >>
>>> >> Just copying what avi and mov muxer do.
>>> >>
>>> >> Note that (many) decoders print errors and (can) continue.
>>> >>
>>> >> (I believe library users can - and do - put rawvideo into standard
>>> >> containers and force the right pix_fmt on reading.)
>>> >
>>> > That seems silly, we shouldn't log an error that a file will be broken
>>> > and then still write it. Muxers should be strict and write only valid
>>> > files.
>>>
>>> This is what we currently do for both other multi-purpose containers
>>> (while FFmpeg logs no message for unreadable transport streams),
>>> so lets please commit this.
>>
>> I have to agree with Hendrik. Your patch is all about adding a message
>> for this case.
>
> The same message that gets printed for the other general-purpose
> muxers.
>
>> Why not do the right thing in the first place?
>
> I believe informing users is the right thing.
>
>> You'd only have to add an error return or so.
>
> I would prefer not to harm library users when helping cli users.
>

Protection the world from writing broken unreadable files doesn't harm
anyone either.

- Hendrik