[Ffmpeg-devel] [BUG] no video transcoding

[Baptiste Coudurier]

Michael Niedermayer wrote:
> Hi
> 
> On Mon, Apr 23, 2007 at 10:55:06AM -0000, Wolfram Gloger wrote:
>> Hi,
>>
>>> to comment a little more on this as it seem to be a popular bug ;)
>>>
>>> On Sun, Apr 15, 2007 at 08:13:37AM -0000, Wolfram Gloger wrote:
>>> [...]
>>>> Ok that's probably true -- although I maintain the patch is correct,
>>> no it is not, cur_dts was approximately correct before and completely
>>> wrong after the patch
>> How so?  cur_dts was set to some more or less random packet's dts
>> that was the last one parsed in av_find_stream_info().
> 
> and your proposed patch sets it to the first dts from av_find_stream_info()
> that is equally random
> 
> audio time stamp ?, ?, ?, 5, ?, ?, 123456, 123457, ...
> video time stamp ?, ?, ?, ?, ?, ?, 123456, 123457, ...
> timestamp discontinuity           ^
> 
> the first dts here would be 5 and 123456
> filling things in would lead to something like:
> 
> audio time stamp      5,      6,      7,      5,      6,      7, 123456, ...
> video time stamp 123456, 123457, 123458, 123459, 123460, 123461, 123456, ...
> 
> that is not better than what you get with the last dts, actually its
> worse
> 
> 
>> Then the packet queue is flushed and the next packet read has a
>> (sometimetimes significantly) smaller dts value.
>> This leads to a hard error (dts < cur_dts) for valid DVB streams.
>> It is just a matter of luck if you don't hit this situation.
>>
>> After the patch, cur_dts becomes AV_NO_PTS_VALUE -- how can that
>> be "completely wrong".  Please elaborate.
> 
> its not completly wrong on its own but in combination with all the other
> code it is
> 
> [...]
>> I suspect that reverting 8465 will hide the problem, but
>> please give me until tonight when I will allocate some time
> 
> time is no problem, i can wait, i just want a clean solution ...

Seek regression tests fails with the latest patch posted:

@@ -3302,7 +3302,7 @@
 ret:-1 st:-1 ts:-0.645825 flags:1
 ----------------
 data/b-libav.ts
-ret: 0 st: 0 dts:95443.677689 pts:95443.717689 pos:-1 size:24921 flags:1
+ret: 0 st: 0 dts:95443.677689 pts:0.000000 pos:-1 size:24921 flags:1
 ret: 0 st:-1 ts:-1.000000 flags:0
 ret: 0 st: 0 dts:0.000000 pts:-102481911520608.625000 pos:-1 size:22036
flags:1
 ret: 0 st:-1 ts:1.894167 flags:1

-- 
Baptiste COUDURIER                              GnuPG Key Id: 0x5C1ABAAA
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