[FFmpeg-devel] [PATCH] cbs_mpeg2_split_fragment(): cache the buffer end
Scott Theisen
scott.the.elm at gmail.com
Fri Sep 16 20:41:43 EEST 2022
Ping; it still applies cleanly.
-Scott Theisen
On 5/15/22 14:50, Scott Theisen wrote:
> Ping; it still applies cleanly.
>
> -Scott Theisen
>
> On 2/8/22 15:32, Scott Theisen wrote:
>> Also add a few clarifying comments.
>> ---
>> libavcodec/cbs_mpeg2.c | 16 ++++++++--------
>> 1 file changed, 8 insertions(+), 8 deletions(-)
>>
>> diff --git a/libavcodec/cbs_mpeg2.c b/libavcodec/cbs_mpeg2.c
>> index 33bd3e0998..47732562d1 100644
>> --- a/libavcodec/cbs_mpeg2.c
>> +++ b/libavcodec/cbs_mpeg2.c
>> @@ -144,12 +144,12 @@ static int
>> cbs_mpeg2_split_fragment(CodedBitstreamContext *ctx,
>> CodedBitstreamFragment *frag,
>> int header)
>> {
>> - const uint8_t *start;
>> + const uint8_t *start = frag->data;
>> + const uint8_t * const buf_end = frag->data + frag->data_size;
>> uint32_t start_code = -1;
>> int err;
>> - start = avpriv_find_start_code(frag->data, frag->data +
>> frag->data_size,
>> - &start_code);
>> + start = avpriv_find_start_code(start, buf_end, &start_code);
>> if (start_code >> 8 != 0x000001) {
>> // No start code found.
>> return AVERROR_INVALIDDATA;
>> @@ -165,12 +165,11 @@ static int
>> cbs_mpeg2_split_fragment(CodedBitstreamContext *ctx,
>> // start code in any way (as e.g. happens when there is a
>> // Sequence End unit at the very end of a packet).
>> start_code = UINT32_MAX;
>> - end = avpriv_find_start_code(start--, frag->data +
>> frag->data_size,
>> - &start_code);
>> -
>> - // start points to the byte containing the
>> start_code_identifier
>> + end = avpriv_find_start_code(start, buf_end, &start_code);
>> + start--;
>> + // decrement so start points to the byte containing the
>> start_code_identifier
>> // (may be the last byte of fragment->data); end points to
>> the byte
>> - // following the byte containing the start code identifier
>> (or to
>> + // following the byte containing the next start code
>> identifier (or to
>> // the end of fragment->data).
>> if (start_code >> 8 == 0x000001) {
>> // Unit runs from start to the beginning of the start code
>> @@ -178,6 +177,7 @@ static int
>> cbs_mpeg2_split_fragment(CodedBitstreamContext *ctx,
>> unit_size = (end - 4) - start;
>> } else {
>> // We didn't find a start code, so this is the final unit.
>> + // There is no start code to remove from end, hence not
>> (end - 4).
>> unit_size = end - start;
>> }
>
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