[FFmpeg-devel] [PATCH v2] avformat/mpegts: add option max_packet_size

[Gyan Doshi]

On 2022-01-16 01:39 am, Marton Balint wrote:
>
>
> On Sat, 15 Jan 2022, Gyan Doshi wrote:
>
>> Plan to push tomorrow.
>>
>> On 2022-01-12 08:57 pm, Gyan Doshi wrote:
>>>  Makes maximum size of emitted packet user-tunable.
>>>  ---
>>>    doc/demuxers.texi    | 4 ++++
>>>    libavformat/mpegts.c | 9 ++++++---
>>>    2 files changed, 10 insertions(+), 3 deletions(-)
>>>
>>>  diff --git a/doc/demuxers.texi b/doc/demuxers.texi
>>>  index 26ae768d7a..aef5976551 100644
>>>  --- a/doc/demuxers.texi
>>>  +++ b/doc/demuxers.texi
>>>  @@ -775,6 +775,10 @@ disabled). Default value is -1.
>>>    @item merge_pmt_versions
>>>    Re-use existing streams when a PMT's version is updated and 
>>> elementary
>>>    streams move to different PIDs. Default value is 0.
>>>  +
>>>  + at item max_packet_size
>>>  +Set maximum size, in bytes, of packet emitted by the demuxer. 
>>> Payloads
>>>  above this size
>>>  +are split across multiple packets. Range is 1 to INT_MAX. Default is
>>>  204800 bytes.
>>>    @end table
>>>
>>>    @section mpjpeg
>>>  diff --git a/libavformat/mpegts.c b/libavformat/mpegts.c
>>>  index 2479cb6f7d..6ff1a54706 100644
>>>  --- a/libavformat/mpegts.c
>>>  +++ b/libavformat/mpegts.c
>>>  @@ -162,6 +162,7 @@ struct MpegTSContext {
>>>
>>>        int resync_size;
>>>        int merge_pmt_versions;
>>>  +    int max_packet_size;
>>>
>>>        /******************************************/
>>>        /* private mpegts data */
>>>  @@ -198,6 +199,8 @@ static const AVOption options[] = {
>>>        {.i64 = 0}, 0, 1, 0 },
>>>        {"skip_clear", "skip clearing programs", offsetof(MpegTSContext,
>>>        skip_clear), AV_OPT_TYPE_BOOL,
>>>         {.i64 = 0}, 0, 1, 0 },
>>>  +    {"max_packet_size", "maximum size of emitted packet",
>>>  offsetof(MpegTSContext, max_packet_size), AV_OPT_TYPE_INT,
>>>  +     {.i64 = MAX_PES_PAYLOAD}, 1, INT_MAX, 
>>> AV_OPT_FLAG_DECODING_PARAM },
>
> INT_MAX/2 might be better to avoid possible overflows with padding or 
> pes header. Or simply 1 GiB, after all, a corrupt PID might consume 
> RAM up to this amount, so preferably it should not be too big... Docs 
> needs update accordingly.
>
> Also since MAX_PES_PAYLOAD define is no longer used in the code, I'd 
> just remove it and put its value directly here as the default.

Will change to INT_MAX/2 and push.

Thanks,
Gyan