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Commit 04ed61b1 authored by Martin Storsjo's avatar Martin Storsjo
Browse files

avcenc: Only do startcode escaping if the next byte requires it 

Section 7.4.1 in the H.264 standard says that the only valid bytes
to follow a sequence that starts with 0x000003 are 0x00, 0x01,
0x02 or 0x03.

This makes EncodeDecodeTest pass properly when decoding using
OMX.google.h264.decoder, which is strict about the forbidden
escape sequences.

Change-Id: Ice113d9b934015003ea9cb10d0b21cee4d18d774
parent 5930e8eb

media/libstagefright/codecs/avc/enc/src/bitstream_io.cpp

+9 −6
Original line number Diff line number Diff line
@@ -103,6 +103,15 @@ AVCEnc_Status AVCBitstreamSaveWord(AVCEncBitstream *stream) 
    {

        num_bits -= 8;

        byte = (current_word >> num_bits) & 0xFF;

        if (stream->count_zeros == 2)

        {   /* for num_bits = 32, this can add 2 more bytes extra for EPBS */

            if (byte <= 3)

            {

                *write_pnt++ = 0x3;

                stream->write_pos++;

                stream->count_zeros = 0;

            }

        }

        if (byte != 0)

        {

            *write_pnt++ = byte;
@@ -114,12 +123,6 @@ AVCEnc_Status AVCBitstreamSaveWord(AVCEncBitstream *stream) 
            stream->count_zeros++;

            *write_pnt++ = byte;

            stream->write_pos++;

            if (stream->count_zeros == 2)

            {   /* for num_bits = 32, this can add 2 more bytes extra for EPBS */

                *write_pnt++ = 0x3;

                stream->write_pos++;

                stream->count_zeros = 0;

            }

        }

    }