/**
* This struct describes the properties of an encoded stream.
*
* sizeof(AVCodecParameters) is not a part of the public ABI, this struct must
* be allocated with avcodec_parameters_alloc() and freed with
* avcodec_parameters_free().
*/
typedef struct AVCodecParameters {
/**
* General type of the encoded data.
*/
enum AVMediaType codec_type;
/**
* Specific type of the encoded data (the codec used).
*/
enum AVCodecID codec_id;
/**
* Additional information about the codec (corresponds to the AVI FOURCC).
*/
uint32_t codec_tag; /**
* Extra binary data needed for initializing the decoder, codec-dependent.
*
* Must be allocated with av_malloc() and will be freed by
* avcodec_parameters_free(). The allocated size of extradata must be at
* least extradata_size + AV_INPUT_BUFFER_PADDING_SIZE, with the padding
* bytes zeroed.
*/
uint8_t *extradata;
/**
* Size of the extradata content in bytes.
*/
int extradata_size; /**
* - video: the pixel format, the value corresponds to enum AVPixelFormat.
* - audio: the sample format, the value corresponds to enum AVSampleFormat.
*/
int format; /**
* The average bitrate of the encoded data (in bits per second).
*/
int64_t bit_rate; int bits_per_coded_sample; /**
* Codec-specific bitstream restrictions that the stream conforms to.
*/
int profile;
int level; /**
* Video only. The dimensions of the video frame in pixels.
*/
int width;
int height; /**
* Video only. The aspect ratio (width / height) which a single pixel
* should have when displayed.
*
* When the aspect ratio is unknown / undefined, the numerator should be
* set to 0 (the denominator may have any value).
*/
AVRational sample_aspect_ratio; /**
* Video only. The order of the fields in interlaced video.
*/
enum AVFieldOrder field_order; /**
* Video only. Additional colorspace characteristics.
*/
enum AVColorRange color_range;
enum AVColorPrimaries color_primaries;
enum AVColorTransferCharacteristic color_trc;
enum AVColorSpace color_space;
enum AVChromaLocation chroma_location; /**
* Video only. Number of delayed frames.
*/
int video_delay; /**
* Audio only. The channel layout bitmask. May be 0 if the channel layout is
* unknown or unspecified, otherwise the number of bits set must be equal to
* the channels field.
*/
uint64_t channel_layout;
/**
* Audio only. The number of audio channels.
*/
int channels;
/**
* Audio only. The number of audio samples per second.
*/
int sample_rate;
/**
* Audio only. The number of bytes per coded audio frame, required by some
* formats.
*
* Corresponds to nBlockAlign in WAVEFORMATEX.
*/
int block_align;
/**
* Audio only. Audio frame size, if known. Required by some formats to be static.
*/
int frame_size; /**
* Audio only. The amount of padding (in samples) inserted by the encoder at
* the beginning of the audio. I.e. this number of leading decoded samples
* must be discarded by the caller to get the original audio without leading
* padding.
*/
int initial_padding;
/**
* Audio only. The amount of padding (in samples) appended by the encoder to
* the end of the audio. I.e. this number of decoded samples must be
* discarded by the caller from the end of the stream to get the original
* audio without any trailing padding.
*/
int trailing_padding;
/**
* Audio only. Number of samples to skip after a discontinuity.
*/
int seek_preroll;
} AVCodecParameters;
enum AVMediaType codec_type：编解码器的类型（视频，音频...）
enum AVCodecID codec_id：标示特定的编解码器
int format：对于视频来说就是像素格式(参见AVPixelFormat,如0就代表YUV420p)，对于音频来说就是采样数据格式(参见AVSampleFormat)。
int bit_rate：平均比特率
uint8_t *extradata; int extradata_size：针对特定编码器包含的附加信息（例如对于H.264解码器来说，存储SPS，PPS等）
int width, height：如果是视频的话，代表视频帧的宽和高
int refs：运动估计参考帧的个数（H.264的话会有多帧，MPEG2这类的一般就没有了）
int sample_rate：采样率（音频）
uint64_t channel_layout：声道格式
int channels：声道数（音频）
int profile：型（H.264里面就有，其他编码标准应该也有）
int level：级（和profile差不太多）
使用方法，可以从 AVStream 上获取 AVCodecParameters ，例：
for (int i = ; i < ic->nb_streams; i++) {
AVStream *as = ic->streams[i];
if (as->codecpar->codec_type == AVMEDIA_TYPE_VIDEO) {
LOGI("视频数据");
videoStream = i;
fps = r2d(as->avg_frame_rate);
LOGI("fps = %d, width = %d, height = %d, codecid = %d, pixformat = %d, bit_rate = %lld", fps,
as->codecpar->width,
as->codecpar->height,
as->codecpar->codec_id,
as->codecpar->format,
as->codecpar->bit_rate
);
}
else {
LOGI("音频数据");
audioStream = i;
LOGI("sample_rate = %d, channels = %d, sample_format = %d",
as->codecpar->sample_rate,
as->codecpar->channels,
as->codecpar->format
);
}
}
打印：
2019-04-03 21:16:26.064 29619-29619/? I/xp.chen: 视频数据
2019-04-03 21:16:26.064 29619-29619/? I/xp.chen: fps = 25, width = 1920, height = 1080, codecid = 28, pixformat = 0, bit_rate = 3312568
2019-04-03 21:16:26.064 29619-29619/? I/xp.chen: 音频数据
2019-04-03 21:16:26.064 29619-29619/? I/xp.chen: sample_rate = 44100, channels = 2, sample_format = 8