C++ AP4_Sample类代码示例

/*----------------------------------------------------------------------
|   AP4_HintTrackReader::WriteSampleRtpData
+---------------------------------------------------------------------*/
AP4_Result
AP4_HintTrackReader::WriteSampleRtpData(AP4_SampleRtpConstructor* constructor, 
                                        AP4_ByteStream*           data_stream)
{
    AP4_Track* referenced_track = NULL;
    if (constructor->GetTrackRefIndex() == 0xFF) {
        // data is in the hint track
        referenced_track = &m_HintTrack;
    } else {
        // check if we have a media track
        if (m_MediaTrack == NULL) return AP4_FAILURE;
        referenced_track = m_MediaTrack;
    }

    // write the sample data
    AP4_Sample sample;
    AP4_Result result = referenced_track->GetSample(constructor->GetSampleNum()-1, // adjust
                                                    sample);
    if (AP4_FAILED(result)) return result;
    AP4_DataBuffer buffer(constructor->GetLength());
    result = sample.ReadData(
        buffer, constructor->GetLength(), constructor->GetSampleOffset());
    if (AP4_FAILED(result)) return result;

    // write the data
    return data_stream->Write(buffer.GetData(), buffer.GetDataSize());
}

/*----------------------------------------------------------------------
|   AP4_MarlinIpmpTrackDecrypter:GetProcessedSampleSize
+---------------------------------------------------------------------*/
AP4_Size 
AP4_MarlinIpmpTrackDecrypter::GetProcessedSampleSize(AP4_Sample& sample)
{
    // with CBC, we need to decrypt the last block to know what the padding was
    AP4_Size       encrypted_size = sample.GetSize()-AP4_AES_BLOCK_SIZE;
    AP4_DataBuffer encrypted;
    AP4_DataBuffer decrypted;
    AP4_Size       decrypted_size = AP4_CIPHER_BLOCK_SIZE;
    if (sample.GetSize() < 2*AP4_CIPHER_BLOCK_SIZE) {
        return 0;
    }
    AP4_Size offset = sample.GetSize()-2*AP4_CIPHER_BLOCK_SIZE;
    if (AP4_FAILED(sample.ReadData(encrypted, 2*AP4_CIPHER_BLOCK_SIZE, offset))) {
        return 0;
    }
    decrypted.Reserve(decrypted_size);
    m_Cipher->SetIV(encrypted.GetData());
    if (AP4_FAILED(m_Cipher->ProcessBuffer(encrypted.GetData()+AP4_CIPHER_BLOCK_SIZE, 
                                           AP4_CIPHER_BLOCK_SIZE,
                                           decrypted.UseData(), 
                                           &decrypted_size, 
                                           true))) {
        return 0;
    }
    unsigned int padding_size = AP4_CIPHER_BLOCK_SIZE-decrypted_size;
    return encrypted_size-padding_size;
}

/*----------------------------------------------------------------------
|   AutoDetectAudioFragmentDuration
+---------------------------------------------------------------------*/
static unsigned int 
AutoDetectAudioFragmentDuration(AP4_ByteStream& stream, TrackCursor* cursor)
{
    // remember where we are in the stream
    AP4_Position where = 0;
    stream.Tell(where);
    AP4_LargeSize stream_size = 0;
    stream.GetSize(stream_size);
    AP4_LargeSize bytes_available = stream_size-where;
    
    AP4_UI64  fragment_count = 0;
    AP4_UI32  last_fragment_size = 0;
    AP4_Atom* atom = NULL;
    while (AP4_SUCCEEDED(AP4_DefaultAtomFactory::Instance.CreateAtomFromStream(stream, bytes_available, atom))) {
        if (atom && atom->GetType() == AP4_ATOM_TYPE_MOOF) {
            AP4_ContainerAtom* moof = AP4_DYNAMIC_CAST(AP4_ContainerAtom, atom);
            AP4_TfhdAtom* tfhd = AP4_DYNAMIC_CAST(AP4_TfhdAtom, moof->FindChild("traf/tfhd"));
            if (tfhd && tfhd->GetTrackId() == cursor->m_Track->GetId()) {
                ++fragment_count;
                AP4_TrunAtom* trun = AP4_DYNAMIC_CAST(AP4_TrunAtom, moof->FindChild("traf/trun"));
                if (trun) {
                    last_fragment_size = trun->GetEntries().ItemCount();
                }
            }
        }
        delete atom;
        atom = NULL;
    }
    
    // restore the stream to its original position
    stream.Seek(where);
    
    // decide if we can infer an fragment size
    if (fragment_count == 0 || cursor->m_Samples->GetSampleCount() == 0) {
        return 0;
    }
    // don't count the last fragment if we have more than one
    if (fragment_count > 1 && last_fragment_size) {
        --fragment_count;
    }
    if (fragment_count <= 1 || cursor->m_Samples->GetSampleCount() < last_fragment_size) {
        last_fragment_size = 0;
    }
    AP4_Sample sample;
    AP4_UI64 total_duration = 0;
    for (unsigned int i=0; i<cursor->m_Samples->GetSampleCount()-last_fragment_size; i++) {
        cursor->m_Samples->GetSample(i, sample);
        total_duration += sample.GetDuration();
    }
    return (unsigned int)AP4_ConvertTime(total_duration/fragment_count, cursor->m_Track->GetMediaTimeScale(), 1000);
}

/*----------------------------------------------------------------------
|   AutoDetectFragmentDuration
+---------------------------------------------------------------------*/
static unsigned int 
AutoDetectFragmentDuration(TrackCursor* cursor)
{
    AP4_Sample   sample;
    unsigned int sample_count = cursor->m_Samples->GetSampleCount();
    
    // get the first sample as the starting point
    AP4_Result result = cursor->m_Samples->GetSample(0, sample);
    if (AP4_FAILED(result)) {
        fprintf(stderr, "ERROR: failed to read first sample\n");
        return 0;
    }
    if (!sample.IsSync()) {
        fprintf(stderr, "ERROR: first sample is not an I frame\n");
        return 0;
    }
    
    for (unsigned int interval = 1; interval < sample_count; interval++) {
        bool irregular = false;
        unsigned int sync_count = 0;
        unsigned int i;
        for (i = 0; i < sample_count; i += interval) {
            result = cursor->m_Samples->GetSample(i, sample);
            if (AP4_FAILED(result)) {
                fprintf(stderr, "ERROR: failed to read sample %d\n", i);
                return 0;
            }
            if (!sample.IsSync()) {
                irregular = true;
                break;
            }
            ++sync_count;
        }
        if (sync_count < 1) continue;
        if (!irregular) {
            // found a pattern
            AP4_UI64 duration = sample.GetDts();
            double fps = (double)(interval*(sync_count-1))/((double)duration/(double)cursor->m_Track->GetMediaTimeScale());
            if (Options.verbosity > 0) {
                printf("found regular I-frame interval: %d frames (at %.3f frames per second)\n",
                       interval, (float)fps);
            }
            return (unsigned int)(1000.0*(double)interval/fps);
        }
    }
    
    return 0;
}

/*----------------------------------------------------------------------
|   AP4_OmaDcfCbcSampleEncrypter::GetEncryptedSampleSize
+---------------------------------------------------------------------*/
AP4_Size
AP4_OmaDcfCbcSampleEncrypter::GetEncryptedSampleSize(AP4_Sample& sample)
{
    AP4_Size sample_size = sample.GetSize();
    AP4_Size padding_size = AP4_CIPHER_BLOCK_SIZE-(sample_size%AP4_CIPHER_BLOCK_SIZE);
    return sample_size+padding_size+AP4_CIPHER_BLOCK_SIZE+1;
}

/*----------------------------------------------------------------------
|   AP4_LinearReader::PopSample
+---------------------------------------------------------------------*/
bool
AP4_LinearReader::PopSample(Tracker*        tracker,
                            AP4_Sample&     sample,
                            AP4_DataBuffer& sample_data)
{
    SampleBuffer* head = NULL;
    if (AP4_SUCCEEDED(tracker->m_Samples.PopHead(head))) {
        assert(head->m_Sample);
        sample = *head->m_Sample;
        sample_data.SetData(head->m_Data.GetData(), head->m_Data.GetDataSize());
        assert(m_BufferFullness >= sample.GetSize());
        m_BufferFullness -= sample.GetSize();
        delete head;
        return true;
    }

    return false;
}

/*----------------------------------------------------------------------
|   AP4_DecryptingSampleReader::ReadSampleData
+---------------------------------------------------------------------*/
AP4_Result 
AP4_DecryptingSampleReader::ReadSampleData(AP4_Sample&     sample, 
                                           AP4_DataBuffer& sample_data)
{
    AP4_Result result = sample.ReadData(m_DataBuffer);
    if (AP4_FAILED(result)) return result;

    return m_Decrypter->DecryptSampleData(m_DataBuffer, sample_data);
}

 virtual AP4_Result GetSample(AP4_Ordinal index, AP4_Sample& sample) {
     AP4_Result result = m_Track->GetSample(index, sample);
     if (AP4_SUCCEEDED(result)) {
         if (m_ForcedSync[index]) {
             sample.SetSync(true);
         }
     }
     return result;
 }

/*----------------------------------------------------------------------
|       AP4_IsmaTrackDecrypter::GetProcessedSampleSize
+---------------------------------------------------------------------*/
AP4_Size   
AP4_IsmaTrackDecrypter::GetProcessedSampleSize(AP4_Sample& sample)
{
    AP4_Size isma_header_size = 
        m_CipherParams->GetKeyIndicatorLength() +
        m_CipherParams->GetIvLength();
    if (m_CipherParams->GetSelectiveEncryption()) {
        isma_header_size++;
    }
    return sample.GetSize()-isma_header_size;
}

/*----------------------------------------------------------------------
|   IsIFrame
+---------------------------------------------------------------------*/
static bool
IsIFrame(AP4_Sample& sample, AP4_AvcSampleDescription* avc_desc) {
    AP4_DataBuffer sample_data;
    if (AP4_FAILED(sample.ReadData(sample_data))) {
        return false;
    }

    const unsigned char* data = sample_data.GetData();
    AP4_Size             size = sample_data.GetDataSize();

    while (size >= avc_desc->GetNaluLengthSize()) {
        unsigned int nalu_length = 0;
        if (avc_desc->GetNaluLengthSize() == 1) {
            nalu_length = *data++;
            --size;
        } else if (avc_desc->GetNaluLengthSize() == 2) {
            nalu_length = AP4_BytesToUInt16BE(data);
            data += 2;
            size -= 2;
        } else if (avc_desc->GetNaluLengthSize() == 4) {
            nalu_length = AP4_BytesToUInt32BE(data);
            data += 4;
            size -= 4;
        } else {
            return false;
        }
        if (nalu_length <= size) {
            size -= nalu_length;
        } else {
            size = 0;
        }
        
        switch (*data & 0x1F) {
            case 1: {
                AP4_BitStream bits;
                bits.WriteBytes(data+1, 8);
                ReadGolomb(bits);
                unsigned int slice_type = ReadGolomb(bits);
                if (slice_type == 2 || slice_type == 7) {
                    return true;
                } else {
                    return false; // only show first slice type
                }
            }
            
            case 5: 
                return true;
        }
        
        data += nalu_length;
    }
 
    return false;
}

/*----------------------------------------------------------------------
|   AP4_Track::Clone
+---------------------------------------------------------------------*/
AP4_Track* 
AP4_Track::Clone(AP4_Result* result)
{
    AP4_SyntheticSampleTable* sample_table = new AP4_SyntheticSampleTable();
    
    // default return value
    if (result) *result = AP4_SUCCESS;
    
    // add clones of the sample descriptions to the new sample table
    for (unsigned int i=0; ;i++) {
        AP4_SampleDescription* sample_description = GetSampleDescription(i);
        if (sample_description == NULL) break;
        sample_table->AddSampleDescription(sample_description->Clone());
    }

    AP4_Sample  sample;
    AP4_Ordinal index = 0;
    while (AP4_SUCCEEDED(GetSample(index, sample))) {
        AP4_ByteStream* data_stream;
        data_stream = sample.GetDataStream();
        sample_table->AddSample(*data_stream,
                                sample.GetOffset(),
                                sample.GetSize(),
                                sample.GetDuration(),
                                sample.GetDescriptionIndex(),
                                sample.GetDts(),
                                sample.GetCtsDelta(),
                                sample.IsSync());
        AP4_RELEASE(data_stream); // release our ref, the table has kept its own ref.
        index++;
    }    
    
    // create the cloned track
    AP4_Track* clone = new AP4_Track(GetType(),
                                     sample_table,
                                     GetId(),
                                     GetMovieTimeScale(),
                                     GetDuration(),
                                     GetMediaTimeScale(),
                                     GetMediaDuration(),
                                     GetTrackLanguage(),
                                     GetWidth(),
                                     GetHeight());
                                     
    return clone;
}

/*----------------------------------------------------------------------
|       AP4_Track::ReadSample
+---------------------------------------------------------------------*/
AP4_Result   
AP4_Track::ReadSample(AP4_Ordinal     index, 
                      AP4_Sample&     sample,
                      AP4_DataBuffer& data)
{
    AP4_Result result;

    // get the sample
    result = GetSample(index, sample);
    if (AP4_FAILED(result)) return result;

    // read the data
    return sample.ReadData(data);
}

AP4_Result SampleFileStorage::StoreSample(AP4_Sample& from_sample, AP4_Sample& to_sample) {
    // clone the sample fields
    to_sample = from_sample;

    // read the sample data
    AP4_DataBuffer sample_data;
    AP4_Result result = from_sample.ReadData(sample_data);
    if (AP4_FAILED(result)) return result;

    // mark where we are going to store the sample data
    AP4_Position position;
    m_Stream->Tell(position);
    to_sample.SetOffset(position);

    // write the sample data
    result = m_Stream->Write(sample_data.GetData(), sample_data.GetDataSize());
    if (AP4_FAILED(result)) return result;

    // update the stream for the new sample
    to_sample.SetDataStream(*m_Stream);

    return AP4_SUCCESS;
}

/*----------------------------------------------------------------------
|   ReadSample
+---------------------------------------------------------------------*/
static AP4_Result
ReadSample(SampleReader&   reader, 
           AP4_Track&      track,
           AP4_Sample&     sample,
           AP4_DataBuffer& sample_data, 
           double&         ts,
           bool&           eos)
{
    AP4_Result result = reader.ReadSample(sample, sample_data);
    if (AP4_FAILED(result)) {
        if (result == AP4_ERROR_EOS) {
            eos = true;
        } else {
            return result;
        }
    }
    ts = (double)sample.GetDts()/(double)track.GetMediaTimeScale();
    
    return AP4_SUCCESS;
}

/*----------------------------------------------------------------------
|   ShowSample
+---------------------------------------------------------------------*/
static void
ShowSample(AP4_Sample& sample, unsigned int index, AP4_SampleDecrypter* sample_decrypter)
{
    printf("[%06d] size=%6d duration=%6d", 
           index, 
           (int)sample.GetSize(), 
           (int)sample.GetDuration());
    printf(" offset=%10lld dts=%10lld cts=%10lld ", 
           sample.GetOffset(),
           sample.GetDts(), 
           sample.GetCts());
    if (sample.IsSync()) {
        printf(" [S] ");
    } else {
        printf("     ");
    }

    AP4_DataBuffer sample_data;
    sample.ReadData(sample_data);
    AP4_DataBuffer* data = &sample_data;
    
    AP4_DataBuffer decrypted_sample_data;
    if (sample_decrypter) {
        sample_decrypter->DecryptSampleData(sample_data, decrypted_sample_data);
        data = & decrypted_sample_data;
    }
    
    unsigned int show = data->GetDataSize();
    if (show > 12) show = 12; // max first 12 chars
    
    for (unsigned int i=0; i<show; i++) {
        printf("%02x", data->GetData()[i]);
    }
    if (show == data->GetDataSize()) {
        printf("\n");
    } else {
        printf("...\n");
    }
}