[FFmpeg-devel] [PATCH 2/2] lavf/avienc: Add xxpc entries to index

[Mats Peterson]

On 03/12/2016 04:29 PM, Michael Niedermayer wrote:
> On Sat, Mar 12, 2016 at 02:54:45PM +0100, Mats Peterson wrote:
>> On 03/12/2016 02:52 PM, Michael Niedermayer wrote:
>>> On Sat, Mar 12, 2016 at 02:36:59PM +0100, Mats Peterson wrote:
>>>> On 03/12/2016 02:26 PM, Mats Peterson wrote:
>>>>> On 03/12/2016 12:53 PM, Michael Niedermayer wrote:
>>>>>> On Sat, Mar 12, 2016 at 07:14:16AM +0100, Mats Peterson wrote:
>>>>>>> Here's an interesting one. Windows Media Player won't make any palette
>>>>>>> changes without the xxpc chunks beeing indexed.
>>>>>>>
>>>>>>> Fixing the logic for reading and seeking with xxpc chunks in the
>>>>>>> demuxer  is a future task. Now the muxing of video with xxpc chunks
>>>>>>> works properly at least.
>>>>>>>
>>>>>>> Try playing the resulting test.avi file from the command line below
>>>>>>> with Windows Media Player, with and without this patch.
>>>>>>>
>>>>>>> ffmpeg -i TOON.AVI -c:v copy -c:a copy test.avi
>>>>>>>
>>>>>>> Mats
>>>>>>>
>>>>>>> --
>>>>>>> Mats Peterson
>>>>>>> http://matsp888.no-ip.org/~mats/
>>>>>>
>>>>>>>   libavformat/avi.h            |    6 +++-
>>>>>>>   libavformat/avienc.c         |   56
>>>>>>> +++++++++++++++++++++++++++++++++----------
>>>>>>>   tests/ref/lavf-fate/avi_cram |    4 +--
>>>>>>>   3 files changed, 51 insertions(+), 15 deletions(-)
>>>>>>> 2cf2565f9e258ee1a2bfcb83e4f30ecb1c13296d
>>>>>>> 0002-Add-xxpc-entries-to-index.patch
>>>>>>>  From 50f6c1dd38f503e77d53e0e6cdbadfe511282126 Mon Sep 17 00:00:00 2001
>>>>>>> From: Mats Peterson <matsp888 at yahoo.com>
>>>>>>> Date: Sat, 12 Mar 2016 07:00:33 +0100
>>>>>>> Subject: [PATCH 2/2] lavf/avienc: Add xxpc entries to index
>>>>>>>
>>>>>>> ---
>>>>>>>   libavformat/avi.h            |    6 ++++-
>>>>>>>   libavformat/avienc.c         |   56
>>>>>>> +++++++++++++++++++++++++++++++++---------
>>>>>>>   tests/ref/lavf-fate/avi_cram |    4 +--
>>>>>>>   3 files changed, 51 insertions(+), 15 deletions(-)
>>>>>>>
>>>>>>> diff --git a/libavformat/avi.h b/libavformat/avi.h
>>>>>>> index 34da76f..af21f2c 100644
>>>>>>> --- a/libavformat/avi.h
>>>>>>> +++ b/libavformat/avi.h
>>>>>>> @@ -32,7 +32,11 @@
>>>>>>>   #define AVI_MASTER_INDEX_SIZE   256
>>>>>>>   #define AVI_MAX_STREAM_COUNT    100
>>>>>>>
>>>>>>> +/* stream header flags */
>>>>>>> +#define AVISF_VIDEO_PALCHANGES  0x00010000
>>>>>>> +
>>>>>>>   /* index flags */
>>>>>>> -#define AVIIF_INDEX             0x10
>>>>>>> +#define AVIIF_INDEX             0x00000010
>>>>>>> +#define AVIIF_NO_TIME           0x00000100
>>>>>>>
>>>>>>>   #endif /* AVFORMAT_AVI_H */
>>>>>>> diff --git a/libavformat/avienc.c b/libavformat/avienc.c
>>>>>>> index ad50379..b731bc2 100644
>>>>>>> --- a/libavformat/avienc.c
>>>>>>> +++ b/libavformat/avienc.c
>>>>>>> @@ -44,13 +44,14 @@
>>>>>>>    */
>>>>>>>
>>>>>>>   typedef struct AVIIentry {
>>>>>>> -    unsigned int flags, pos, len;
>>>>>>> +    char tag[5];
>>>>>>
>>>>>> the tag should be 4 bytes
>>>>>> 5 is ugly, it requires padding and bloats the structure with a zero
>>>>>> byte
>>>>>>
>>>>>
>>>>> OK.
>>>>>
>>>>>>
>>>>>>> +    unsigned int flags;
>>>>>>> +    unsigned int pos;
>>>>>>> +    unsigned int len;
>>>>>>>   } AVIIentry;
>>>>>>>
>>>>>>>   #define AVI_INDEX_CLUSTER_SIZE 16384
>>>>>>>
>>>>>>> -#define AVISF_VIDEO_PALCHANGES 0x00010000
>>>>>>> -
>>>>>>>   typedef struct AVIIndex {
>>>>>>>       int64_t     indx_start;
>>>>>>>       int64_t     audio_strm_offset;
>>>>>>
>>>>>>> @@ -612,9 +613,13 @@ static int avi_write_idx1(AVFormatContext *s)
>>>>>>>               }
>>>>>>>               if (!empty) {
>>>>>>>                   avist = s->streams[stream_id]->priv_data;
>>>>>>> -                avi_stream2fourcc(tag, stream_id,
>>>>>>> +                if (*ie->tag)
>>>>>>
>>>>>> ==18406== Conditional jump or move depends on uninitialised value(s,
>>>>>> ==18406==    at 0x598D80: avi_write_idx1 (avienc.c:616)
>>>>>> ==18406==    by 0x599D6D: avi_write_trailer (avienc.c:859)
>>>>>> ==18406==    by 0x64A234: av_write_trailer (mux.c:1124)
>>>>>> ==18406==    by 0x43A729: transcode (ffmpeg.c:4173)
>>>>>> ==18406==    by 0x43ACE3: main (ffmpeg.c:4334)
>>>>>>
>>>>>
>>>>> OK.
>>>>
>>>>
>>>> It's not really uninitalised, is it? Since it isn't used by anything
>>>> but my own code, it's all zero bytes, right?
>>>
>>> after this patch snow encoding failed, i run valgrind and saw this
>>> so there was something wrong, i dont know for sure if it was this
>>>
>>>
>>
>> OK. By the way, are you in the process of applying patch 1 at least?
>
> patch one has a list of exceptions, this list contains every single
> case for which evidence has been provided
> that is all evidence provided so far is consistent in that a biSize
> of 40 is wrong for non palette global headers.

40 is exactly what it should be, in *all* cases, regardless of what 
follows the BITMAPINFOHEADER. Read below.

>
> The spec says:
> "A stream format chunk ('strf') must follow the stream header chunk. The stream format chunk describes the format of the data in the stream. The data contained in this chunk depends on the stream type. For video streams, the information is a BITMAPINFO structure, including palette information if appropriate. For audio streams, the information is a WAVEFORMATEX structure."
>
> If that chunk is a BITMAPINFO structure + a palette then formats
> without a palette would likely have biSize similar to the chunk
> size ...
>
> its quite possible iam missing some details of course ...
>

You're missing the specification of the BITMAPINFOHEADER. It states that 
biSize is the size of the structure, i.e. the BITMAPINFOHEADER itself. 
No less, no more.

https://msdn.microsoft.com/en-us/library/windows/desktop/dd183376%28v=vs.85%29.aspx

Mats